# P1b 5 and 7 SoW IH by ZglvDb5j

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• pg 1
```									AQA GCSE Science: P1b 5.1 How dangerous is a ray of light?
• Electromagnetic radiation travels as waves and moves energy from one place to another.
• All types of electromagnetic waves travel at the same speed through a vacuum (space).
• The electromagnetic spectrum is continuous, but the wavelengths within it can be grouped into types of increasing wavelength and decreasing frequency: gamma rays, X-rays,
ultraviolet rays, visible light, infra-red rays, microwaves and radio waves.
• Electromagnetic waves obey the wave formula:
wave speed        = frequency x wavelength
(metres/second, m/s) (hertz, Hz) (metre, m)

Learning Objectives              Teaching / Learning activities (including How Science Works)                                                    Teaching suggestions
Students should learn:                                                                                                                           • Special needs
• The names of the regions of   Lesson structure                                                                                                • Give the students a large diagram
the electromagnetic spectrum.    Starter                                                                                                         of the electromagnetic spectrum to
• What the term „frequency‟      Rainbow – Get the students to list the colours of the spectrum in order. Then ask                               annotate over the next few lessons.
means in relation to a wave.     them to explain how they can split white light into these colours. (5–10 minutes)                               They can add uses and dangers to it
• That all electromagnetic                                                                                                                       as they go.
What’s a wave? – Give the students a set of cards with wave properties and non-wave properties. Can they
waves travel at the same                                                                                                                         • Provide templates to help the
separate them into two piles? Make sure you include one with „needs a material to travel along‟. (5 minutes)
speed in a vacuum.                                                                                                                               students perform the calculations.
Calculating speed – Can the students remember how to calculate the speed of something? Ask them to
• How to calculate the                                                                                                                           • Gifted and talented
write down the equation and answer a couple of simple speed questions. (10 minutes)
wavelength of an                                                                                                                                 Electromagnetic waves in other
electromagnetic wave.                                                                                                                            media
Main
The students have been told that
• Throughout these next few topics it will be useful to have a large diagram of the electromagnetic
electromagnetic waves all travel at
spectrum on the wall so that you can refer to it regularly.
the same speed in a vacuum, but is
• The students will have studied the electromagnetic spectrum at Key Stage 3, but many will be unfamiliar
this true of other media? They can
with the word „electromagnetic‟.
find out about how the speed
• It is important to get across the idea that the electromagnetic waves travel best through empty space: a
depends on the wavelength and how
vacuum. When doing this, they all travel at the same speed (which is the maximum speed at which anything
this leads to dispersion in prisms
can travel).
and lenses.
• Also emphasise that the spectrum is continuous: there are ranges of each of the regions. This idea can be
• Learning styles
shown by discussing the range of different wavelengths of red pointing out that there is not just one „red‟.
Visual: Drawing wave models.
• When discussing wave diagrams see „Practical support‟.
Intrapersonal: Understanding the
• You may wish to demonstrate some of the devices that use regions of the electromagnetic spectrum.
While doing this, point out that most of them are producing or detecting energy that we cannot see.
• Homework. The students can
• The main difficulty in the calculations will be the rather difficult numbers that electromagnetic waves
reinforce their understanding of the
present. You may find that some calculators cannot cope with them. Standard eight digit calculators cannot
wave equation by trying some
display 300 000 000; you may have to deal with velocities measured in kilometres per second instead.
further calculations.
• The students will have to take great care when performing the calculations and may find them easier if they
„cancel the zeros‟ in some of them, so that they end up with simple calculations like 3/9.                       Risk assessment.
• With students that are more mathematically able, you may wish to use numbers in standard form, e.g. 3.0 x
108 m/s.                                                                                                         None

Pupil development
Pupils produce a poster detailing the uses, dangers, properties and sources of a fraction of the EM spectrum.
This can be mounted on a roll of papers showing the wavelength of light changing. Research can be done
from textbooks or from leaflets available on request.

Plenaries
Quick calculations – Show the students the wavelength of a few electromagnetic waves and ask them to
quickly work out the wave speed and write it on their mini-whiteboard. (5–10 minutes)
More uses – Ask the students to describe one extra use for each of the regions of the electromagnetic
spectrum. (10 minutes)
RMIVUXG? – The students may know an acronym to give the order of the
visible light spectrum (ROYGBIV). Can they think up a method of remembering
the regions of the electromagnetic spectrum? (5–10 minutes)
e.g. Remember My Instructions Visible Under X-ray Glasses
Learning Outcomes                                                                               Practical support
Most students should be able to:                                                                Drawing and labelling waves
• State the parts of the electromagnetic spectrum in order of wavelength.                       Wavelength is a reasonably simple concept, but many mistakes are made drawing
• Give definitions of the words frequency and wavelength.                                       and labelling waves in examinations. Point out that the wavelength can also be
• Describe the properties that all electromagnetic waves have in common.                        measured from trough to trough, or in fact any point in a wave to the next point that
• Use the wave speed equation to calculate wave speed.                                          is doing exactly the same thing. Watch out for students who draw the wavelength
incorrectly; this is usually from the point where the waves crosses zero displacement
Some students should also be able to:                                                           to the next zero, i.e. half a wavelength. A similar problem arises when labelling the
• Rearrange and use the wave speed equation.                                                    amplitude on wave diagrams. This must be from the peak to the zero displacement
position, i.e. half of the „height‟ of the wave not the full „height‟ as many students
http://www.brainpop.com/science/energy/electromagneticspectrum/
Equipment

Pens and sugar paper
Chalk (to draw wave)
Electromagnetic spectrum books / leaflets
AQA GCSE Science: P1b 5.2 Gamma rays and X-rays: reach the parts that other wavelengths cannot reach.
• Different wavelengths of electromagnetic radiation have different effects on living cells. Some radiations . . . . may cause cancerous changes and some may kill cells.
• The uses and hazards associated with the use of each type of radiation in the electromagnetic spectrum.
Students should use their skills, knowledge and understanding of „How Science Works‟:
• to evaluate the possible hazards associated with the use of different types of electromagnetic radiation
• to evaluate methods to reduce exposure to different types of electromagnetic radiation.
Learning Objectives              Teaching / Learning activities (including How Science Works)                                                      Teaching suggestions
Students should learn:                                                                                                                             • Special needs. Present each
• X-rays are used to produce    Lesson structure                                                                                                  student with a photocopy of an X-
images of fractured bones.       Starter                                                                                                           ray photograph so that they can
• Gamma rays are used to         X-ray vision – A certain alien superhero has the ability to see through objects by                                label the areas where the X-rays
sterilise objects and to treat   firing X-rays from his eyes. Ask the students to explain why this would not work                                  pass through or are absorbed.
cancer by radiotherapy.                                                                                                                            • Learning styles
• Both X-rays and gamma          and might not be too healthy for the people he is looking through. (5 minutes)                                    Kinaesthetic: Manipulating and
rays can damage cells or         Definitions – Show the students the key words for this spread, „absorb, reflect, emit‟, and ask them to write     examining X-ray images.
cause cancer by ionisation       down their own definitions. (5–10 minutes)                                                                        Visual: Observing X-rays.
processes.                       What’s up Doc.? – Show the students a range of X-ray photographs and ask them to describe the problems            Auditory: Explaining how X-rays
they see. If you don‟t have originals, then you can find some obvious ones on the Internet. (5–10 minutes)        are produced.
Interpersonal: Discussing injuries.
Main                                                                                                              • ICT link-up. If you have no other
• Start by discussing X-rays. The images are negative; the areas on the film image that are black have            source of X-rays, then the Internet
been exposed to X-rays while the white areas haven’t. This shows that the X-rays have penetrated the              is a great source. To make them
soft tissues but have been absorbed by bones. An Animation is available on the GCSE Science CD to                 more realistic you could photocopy
help explain this.                                                                                                the images onto transparencies.
• This can lead to a discussion of why X-rays are harmful; the energy is absorbed in the body and                 Search on an image search engine
damages cells, particularly cells in bones.                                                                       for phrases like „X-ray jaw‟ and „X-
• You can also discuss the reason X-rays are absorbed by bone; it contains materials that are more dense,         ray chest‟ to find particular injuries.
particularly calcium.                                                                                             You could also find the analyses of
• This absorption by metals can be explained by using X-rays of fillings where the metal absorbs virtually all    the images so you know what is
of the X-rays. X-rays of plates and screws in legs always fascinate.                                              wrong.
• The difference between X-rays and gamma rays is basically how they are produced. X-rays are produced            • Science @ work. The cobalt-60
when high speed electrons are stopped by dense metals; the kinetic energy is converted into the X-rays.           source used in these machines is
Gamma rays are produced by changes in the nuclei of atoms, these nuclear processes will be described in the       very active. One such machine
next chapter.                                                                                                     accidentally ended up being
• When talking about the safety precautions, you might like to ask the students what a dentist or doctor does     recycled in Mexico without the
when taking an X-ray.                                                                                             source being removed first. The
• You may have a film badge to show the students, or you could mock one up from some plastic and                  resulting steel was sent around the
aluminium. These badges offer no protection but they can be used to spot damage after the event.                  world and only discovered when
used in construction in the Los
Pupil Development                                                                                               Alamos research centre in New
Give out X-ray images on acetates and have pupils write a brief description of what each one shows. Why         Mexico, where it set off the
do bones show up but skin and muscles don‟t? What is it that bones have in that cause the difference. What      radiation alarms. At least one
other materials show up vividly?                                                                                person has died from exposure to
Gamma Rays are sometimes used to inspect building safety. How do you think they are used?                       the resulting radiation, possibly
several more.
Plenaries
X-ray safety – Ask the students to draw illustrations showing how dentists or                                   Risk Assessment.
doctors reduce exposure to X-rays or gamma rays. (5–10 minutes)
Radiation danger – Give the students the hazard symbol for ionising radiation and explain what it is            None
supposed to represent. The students should add a list of safety precautions to the symbol; perhaps as icons
below it. (5–10 minutes)
The unknown – X-rays got their name because „x‟ represents the unknown. Can the students think up a
better name for them now that they understand their properties? (5 minutes)

Learning Outcomes                                                                                       Practical support
Most students should be able to:                                                                        X-rays
• Describe how X-rays pass through some materials but not others and this can be used to see the        It may be possible to acquire an X-ray cassette from a local hospital or even
internal structure of some objects.                                                                     dentist. They may also be able to provide help with obtaining X-ray images
• List some of the uses of gamma rays.                                                                  which are much better to handle than copies on paper. There may be
• Describe the effects of gamma rays and X-rays on living cells.                                        confidentiality issues to deal with, but it is worth asking.

Some students should also be able to:                                                                   Equipment
• Explain, in detail, how gamma rays and X-rays damage cells.
X ray acetates
http://www.brainpop.com/science/energy/electromagneticspectrum/
AQA GCSE Science: P1b 5.3 What does a bee see?
• Different wavelengths of electromagnetic radiation are reflected, absorbed or transmitted differently by different substances and types of surface.
• When radiation is absorbed, the energy it carries makes the substance which absorbs it hotter and may create an alternating current with the same frequency as the radiation itself.
• Different wavelengths of electromagnetic radiation have different effects on living cells. Some radiations mostly pass through soft tissue without being absorbed, some produce
heat, some may cause cancerous changes and some may kill cells. These effects depend on the type of radiation and the size of the dose.
Students should use their skills, knowledge and understanding of „How Science Works‟:
• to evaluate the possible hazards associated with the use of different types of electromagnetic radiation
• to evaluate methods to reduce exposure to different types of electromagnetic radiation.
Learning Objectives                      Teaching / Learning activities (including How Science Works)                                            Teaching suggestions
Students should learn:                   Lesson structure                                                                                        • Gifted and talented. Why does the
• Ultraviolet radiation has a higher    Starter                                                                                                 skin become tanned when exposed to
frequency than visible light.            Tanning – Ask the students to describe how to get a suntan or how to avoid                              sunlight? The students could find out
• UV light can be used to cause skin     getting one. (10 minutes)                                                                               what is happening to the skin and
tanning and causes fluorescence.                                                                                                                 how changing colour helps protect the
Filters – Shine a bright white light through a series of filters and ask the students to explain what
• EM waves may be absorbed,                                                                                                                      skin from further damage. They
is happening with a diagram. Use some combinations of filters. (5–10 minutes)
reflected or transmitted by different                                                                                                            should make a brief report on the
Fairground attractions – Can the students come up with explanations why some
media.                                                                                                                                           effects.
clothes glow on fairground rides and discos; ask then to explain where they think the energy comes
• Learning styles
from for this to happen. (5 minutes)
Kinaesthetic: Carrying out suncream
experiments.
Main
Visual: Observing UV effects.
• Show pupils the Ultraviolet powerpoint (see link below) to show that other
Auditory: Explaining fluorescence.
animals such as insects, rats and bird can see colours that we cannot.                                  Interpersonal: Debating the
• It is useful to demonstrate how ultraviolet can be used here, but great care                          healthiness of a tan.
must be taken with ultraviolet lamps and demonstrating fluorescence; see                                Intrapersonal: Evaluating the
‘Practical support’. Many students will have seen the fluorescent effect at                             effectiveness of suncream.
fairgrounds or discos.                                                                                  • ICT link-up. Using a UV detector,
you could monitor the UV levels
• Check that the students understand that the ultraviolet light is being absorbed and the energy is     throughout the day and the students
then being reemitted as visible light; some think that the ink is giving out ultraviolet light.         could explore the results and discuss
• If you have a pair of sunbed „goggles‟ and a ultraviolet photodiode or ultraviolet sensor, you may    what times it is safer to go out in.
like to test them to demonstrate the importance of wearing them.                                        How much longer could you stay out
• During the discussion about the interaction of electromagnetic waves and materials, check             in the morning compared to mid-day,
understanding of the key words, especially „transmitted‟. Use the simple idea that glass transmits      and still get the same dose of UV?
visible light. You might want to use an X-ray and link back to that.
• Try to get across the idea that the waves can carry a signal that can be picked up by a material
when energy is absorbed by it.
Pupils development
Darken the room and let the lamp warm up for a few seconds before use. Shine it onto the washed
cotton and it should glow noticeably (some washing powders seem to work better than others).
Write on an object with the security markers and use the light to reveal the writing. During the
demonstration some students will say that they can see the UV light; make sure you point out that
this is merely violet light that is also produced by the bulb.
      Pupils could also investigate the absorbance of UV light by different
factors of sun cream.
      Debate why it is important to use sun cream. What might someone with sun
cream on look like to a bee!? How does sun cream work?
      Fluorescing materials emit more visible lights than they absorb. What do you
think is going on??
      We also have a recent addition of beads that are white in plain light but fluoress
different colours on exposure to UV light. Possible experiment with sun cream
factors.

Plenaries
UV summary – The students produce a small table summarising the
dangers and uses of UV light. (5–10 minutes)
UV and glass – A glass block absorbs UV light, but transmits visible light. The students must
draw a diagram explaining this without any words. (5–10 minutes)
Cancer cover up – Students design a poster to warn about the dangers of UV radiation causing
skin cancer. (15–20 minutes)
Learning Outcomes                                            Practical support
Most students should be able to:                             Demonstrating fluorescence with UV light
• Describe the uses and dangers associated with UV           Equipment
radiation.                                                   NB: These use of UV equipment is best in a blacked out lab.
• Draw diagrams illustrating the concepts of reflection,     UV lamp – excellent for looking at £10/£20 notes and your drivers licence!
transmission and absorption.                                 UV security marker
Fluoresent materials (Fluorite, highlighters, Cash notes, stamps ect)
Some students should also be able to:                        White cotton recently washed in biological washing powder (or use pupils clothes)
• Explain what happens in reflection, transmission and       Different factors of suncream.
absorption in terms of energy.                               Energy beads, in Petri dishes with sunscreen over in the big UV light thingy from technology

UV lights can damage eyes when directly exposed. You must be cautious with the UV lamp in this demonstration. UV
Ultraviolet.ppt                                              will damage the retina; the lamp must be used so that the students, and yourself, can never look into the bulb. This is
especially important in a darkened room.
AQA GCSE Science: P1b 5.4 Remote controls, microwaves and radios. / Transferring Information
• The uses and the hazards associated with the use of each type of radiation in the electromagnetic spectrum.
• When radiation is absorbed, the energy it carries makes the substance which absorbs it hotter and may create an alternating current with the same frequency as the radiation itself.
Students should use their skills, knowledge and understanding of „How Science Works‟:
• to evaluate the possible hazards associated with the use of different types of electromagnetic radiation
• to evaluate methods to reduce exposure to different types of electromagnetic radiation.
Learning Objectives              Teaching / Learning activities (including How Science Works)                                                      Teaching suggestions
Students should learn:                                                                                                                             • Gifted and talented. If you carry
• How microwaves heat            Lesson structure                                                                                                  out the microwave experiment (and
material when they are           Starter                                                                                                           the transmitter is a polarised one; it
absorbed by water molecules.     Infra-red recap – The students should produce a quick recap of what they know                                     usually is) you may like to
• The ways in which infra-red,   about IR already. A spider diagram would be ideal. (10 minutes)                                                   challenge the students to find an
microwaves and radio waves                                                                                                                         explanation for polarisation. Point
are used in communication                                                                                                                          the transmitter and receiver directly
Main
systems.                                                                                                                                           at each other and switch on to show
• The first part of the lesson is basically a recap on the properties of infra-red radiation.
the maximum signal. Position a
• The students should already be familiar with the heating effect of IR from a previous topic, but it is worth
metal diffraction grille (a set of
showing an IR heater again as reinforcement.
vertical wires) between the
• Demonstrating an infra-red remote control should be fairly simple but the students may not be
aware that the IR can be reflected, so try turning some equipment on by reflecting the signal off the
it. The signal should vary from
whiteboard.
maximum to zero just by rotating
• Students may also be aware of IR transmitters on their mobile phones that can be used to transmit
the plate.
information short distances. You may like to investigate the maximum distance a message can be sent
• Learning styles
from. Discuss why!
Kinaesthetic: Investigating IR
Work through Pages 288/289 of book and answer summery questions in book or use summery
communications in the practical
questions from P1b 5.4 (can be given as H/W)
activity.
• You might be able to block a radio signal by placing an earthed aluminium foil shield around it so that you
Visual: Observing the transmission
can explain that radio waves may be absorbed.
and blocking of signals.
• More modern mobile phones are equipped with Bluetooth technology. You can discuss this as superior
Auditory: Discussing development
communication systems to the IR mentioned above.
of phone communications.
Interpersonal: Making deductions
Plenaries
Wave disasters – How can each type of electromagnetic wave be used to send an emergency or warning
electromagnetic waves.
signal? Can the students think up ideas for all of them (e.g. visible light and lighthouse)? (5–10 minutes)
Intrapersonal: Debating harm
What’s the frequency? – Give the students the frequency of some local radio                                       caused by microwave radiation.
stations and ask them to work out the wavelengths (and vice versa). (10–15
minutes)
Learning Outcomes                                                           Pupil Development
Most students should be able to:
• List the ways in which infra-red waves, microwaves and radio waves are    Testing infra-red signals
used.                                                                       Infra-red signals are able to pass through several paper sheets as long at the batteries on the remote are
• Describe the relationship between the wavelength and frequency of these   in good order.
waves.                                                                      Simply place layers of paper over the transmitter one at a time to find out how many layers are needed
to block the signal. You should find that larger transmitters, such as those for TVs, can send a signal
Some students should also be able to:                                       through at least three sheets. Low-power transmitters, such as those operated by a button cell, struggle
• Describe how alternating currents can be used to produce radio waves.     to get a signal through two sheets.
• Describe how radio waves induce alternating currents in aerials.          Test the distance of transmitting information through mobile phones. Which works better, infra red or
Bluetooth? Why do you think this is?

Equipment.
Pupils can use their mobile phones in this lesson.
Alternatively a Television and remote control can be used.
Meter rules
Paper
IR theremometer
IR heater
W/Sheet P1b 5.4

Risk assessment.
None
AQA GCSE Science: P1b 5.5 Radios, Mobile phones, satellites and televisions
• Radio waves, microwaves, infra-red and visible light can be used for communication.
• Microwaves can pass through the Earth‟s atmosphere and are used to send information to and from satellites and within mobile phone networks.
• Infra-red and visible light can be used to send signals along optical fibres and so travel in curved paths.
Learning Objectives                Teaching / Learning activities (including How Science Works)                                                     Teaching suggestions
Students should learn:                                                                                                                              • Gifted and talented. The students
• That microwaves and radio       Lesson structure                                                                                                 could investigate the relationship
waves are used in mobile           Starter                                                                                                          between wavelength, the size of
phone networks.                    Get the message across – The students must think up as many ways as possible to                                  gaps and the amount of diffraction
• How the atmosphere,              communicate information. List as a mind map on the board and discuss how the                                     that takes place.
including the ionosphere,                                                                                                                           • Learning styles
affects the range that different   information travels. (10 minutes)                                                                                Kinaesthetic: Investigating total
waves can travel.                  Mix up in communications – Give the students a set of cards with communications technologies and                 internal reflection.
• How optical fibres can be        electromagnetic waves and media that carry them and ask them to sort them out. (e.g. TV, radio waves, air).      Visual: Observing optical fibres.
used to carry waves allowing       (10 minutes)                                                                                                     Auditory: Listening to a discussion
them to be contained and           Reflection – Can the students make a device to see around corners and explain how it works? They could           of IT communications systems.
travel around bends due to         just design it or perhaps even make it. (10–15 minutes)                                                          Interpersonal: Collaborating in
total internal reflection.                                                                                                                          practical activity.
Main                                                                                                              Intrapersonal: Considering
• The advantages of using higher frequency waves for communication are important.                                evidence from the practical activity.
• The concept of diffraction may not be well understood; it is typically shown by discussing waves passing       • ICT link-up
• You can show the diffraction effect of waves with a ripple tank.                                               or IT teachers, could present a brief
• Many students will not be aware that the atmosphere has many layers; you may wish to take a bit of time        talk about the schools wireless
and show them a diagram of its structure from the Earth‟s surface to space.                                      network.
• Using a globe to explain how the waves can reach places below the horizon is very helpful. You may find
students‟ geography knowledge is weak when you are discussing communications over long distances, so it
is good to show them the places you are talking about.
• If you are talking about satellite TV, you may wish to briefly mention the geostationary position of the
satellites and the distances involved. With a typical globe (diameter 30cm) the satellite would be nearly 1m
above the surface. This is part of the reason that satellite transmissions for communications show a „time
lag‟.
• Demonstrate or allow the students to discover total internal reflection. See „Practical support‟.
• Demonstrate the optical fibre, see „Practical support‟.
• If you have a model optical fibre, a large curvy block designed to show multiple total internal reflections,
you can show how the ray is contained within the glass; no energy leaves the glass.
• Optical fibres are used in endoscopes in medicine and also by spies and the military for seeing through
walls or around corners. You may be able to find video clips of their use.
Plenaries
Round the bend – Give the students a diagram of an optical fibre in a reasonably
contorted path and ask them to draw the path of a ray that is shown entering the
fibre. (5 minutes)
Sorry for the inconvenience – The students should design a leaflet from a TV or satellite TV company
explaining why the television signal has been poor recently. (15–20 minutes)
Abbreviation dictionary – The students have encountered a lot of abbreviations over the past few lessons;
they should make a list of these and their meanings. (10 minutes)

Learning Outcomes                                                                              Practical support
Most students should be able to:                                                               Optical fibres are easy to demonstrate in a lab even in fairly bright conditions.
• Draw a simple diagram of the ways radio waves travel in the atmosphere.                      Bend the fibre around several objects (perhaps the whole room). Don‟t bend it too much
• State that satellite TV signals are carried by microwaves.                                   though, or the glass may crack; anything smaller than a 10 cm radius is dodgy. Allow
• Draw a diagram explaining how light or infra-red waves travel along an optical fibre.        one student to observe the distant end while you flash a torch into the near end. Even
with the thinnest of fibres, the transmitted light should be obvious. The students can pass
Some students should also be able to:                                                          the fibre end along while the light is flashing.
• Explain why microwaves can be used for satellite communications.
Equipment and materials required
Ripple tank
http://laser.narr.as/laser.swf - a great game where a laser beam can be reflected, refracted   Globe
and split!

Diffraction.ppt – Powerpoint showing the principles of diffraction and fibre optics
AQA GCSE Science: P1b 5.6 Analogue and digital radio, why make the switch?
• Communication signals may be analogue (continuously varying) or digital (only on and off). Digital signals are less prone to interference than analogue and can be processed by
computers.

Learning Objectives               Teaching / Learning activities (including How Science Works)                                                  Teaching suggestions
Students should learn:                                                                                                                          • Special needs. Provide the
• The differences between        Lesson structure                                                                                              students with an analogue signal
analogue (continually             Starter                                                                                                       graph already drawn and a table to
varying) and digital (binary)     Sound quality – Play the students a sound sample from a scratched record (or a real                           fill in. They encode the graph and
information.                      scratched record), ask them to explain what has happened to the sound to reduce the                           then try to redraw it from the
• That digital signals are less   quality. You can also try this with a poor quality video cassette. (10 minutes)                               numbers on another pre-prepared
prone to interference and         Digital storage – How much information can various digital devices store? The students                        set of axes.
noise effects and are simpler     may be aware that a personal music player can hold 5 megabytes, but what does this                            • Gifted and talented. Digital
for computer systems to           mean in terms of songs and in terms of bits? (10 minutes)                                                     messages can become corrupted and
handle.                           Information overload – The students are given a set of cards with devices on them,                            distorted in a number of ways. The
and have to sort them into order by the amount of information (or music) one can                              signal may spread as it passes along
long fibres, or the noise level may
hold. Examples include a LP record, tape, CD, DVD, hard disk, digital video                                   be so high that bits are corrupted.
cassette and human brain. (5 minutes)                                                                         Computer systems are designed to
be able to correct for these errors
Main                                                                                                          automatically. The students can find
• The difference between analogue information and digital information can be shown                            out the basics of these problems and
by showing a CD and a vinyl record. The CD contains a series of very small pits,                              how they are detected and
representing a set of 0s and 1s, while the record has a groove that varies continually                        corrected.
from side to side.                                                                                            • Learning styles
• You may be able to see this groove with a microscope (or better still a video                               Kinaesthetic: Modelling analogue
microscope) but you may have to break the record.                                                             and digital graphs.
• It is important to show some optical fibres to show that visible light can be transmitted                   Visual: Drawing and observing
along it. If you didn‟t do this on the last spread, then use the opportunity here.                            analogue and digital information.
• You should point out how thin the actual fibres are; most of the cable is actually                          Auditory: Listening to differences
protective wrapping to make it easier to handle.                                                              in signal quality.
• Try the analogue to digital conversion activity (see „Practical support‟) to give an idea
of how this conversion can be done. If time is short, you could provide the data to
plot and the students can compare their results with your original.
• You might want to show how a letter can be encoded into binary bits in a byte. For
example in ASCII, see „ICT link-up‟.
• It is simple to show the idea of a carrier wave to transmit a digital signal; just turn a
torch on and off. The signal is the pattern of on and off, while the carrier is the
electromagnetic wave.                                                                       • ICT link-up. In ICT, characters
are encoded into sequences of
• Modulation is a much more difficult concept to get across, especially frequency           binary numbers. A simple system is
modulation. With visible light, amplitude modulation would result in changes of the         called ASCII (American Standard
brightness of the light, while frequency modulation would result in slight changes of       Code for Information Interchange),
colour. Try to discuss these ideas, but don‟t be too worried if there are difficulties.     where each character is represented
• To show how easy it is to recognise a digital signal, show a diagram of a fairly badly    by a pattern of seven bits plus an
corrupted one with noise spikes, and see if the students can translate it back into 0s      error check bit making a total of
and 1s.                                                                                     eight bits or a „byte‟. This allows
for 128 possible characters,
Plenaries                                                                                   including the alphabet, numbers and
Analogue or digital – Give the students a set of cards and ask them if the information or   punctuation symbols. For example
communication method is analogue or digital. Include things like TV signals, MP3            „a‟ is represented by the sequence
players, tape recorders, phone signals, voices, etc. (5 minutes)                            01100001 and „b‟ by 01100010.
Communication crossword – The students should complete a crossword based on the             More modern encoding systems are
electromagnetic spectrum and communications. (15 minutes)                                   more complex allowing millions of
Decoding – Give the students a binary code and a key to decode it, and see who              characters.
can find the exit code first. (5 minutes)
Learning Outcomes                                                     Pupils Development                                                         Activities and extensions
Most students should be able to:                                      Ask the students to draw a set of axes on the graph with 0–7 on the y-     Sending a message through a
• Describe the differences between an analogue and digital signal.    axis representing signal strength, and 0–15 on the x-axis representing     fibre
• List the advantages that digital signal transmission has over       time. They should then draw a random wave along the graph moving           Can the students send a message
analogue.                                                             from left to right. Next they need to digitise this analogue wave. They    through an optical fibre? You can
should convert it into a table of numbers, but only integer numbers are    set them this challenge for
Some students should also be able to:                                 allowed; so for every value of x they must write down the nearest          homework, or as a simple task
• Describe how an analogue signal can be converted to a digital one   whole number on the y-axis. Next they pass this table of data to another   during the lesson. For homework,
and vice-versa.                                                       student, and ask them to plot a graph of the data and connect the points   they would have to come up with an
with a wave without seeing the original. After finishing, they can         encoding system of their own.
Additions                                                             compare the two. Discuss how the copy can be made more accurate            Don‟t tell them what the message is
Diffraction.ppt – The end of this Powerpoint contains a section on    (greater resolution: 0–15 on the y-axis; faster sampling: 0–30 on the x-   going to be in advance.
analogue and digital signals.                                         axis) and what advantages and problems this would have. This method
leaves out the time consuming conversion to binary and back.

Equipment
Graph paper
Rulers

Risk assessment
None
AQA GCSE Science: P1b 5.7 Can mobile phones cook your brain!? Or if Brainiac clip is available “How many mobile phones to boil an egg”
Substantive content that can be revisited in this spread:
• The electromagnetic spectrum is continuous but the wavelengths within it can be grouped into types of increasing wavelength and decreasing frequency: gamma rays, X-rays,
ultraviolet rays, visible light, infra-red rays, microwaves and radio waves.
• The uses and the hazards associated with the use of each type of radiation in the electromagnetic spectrum.
• When radiation is absorbed, the energy it carries makes the substance which absorbs it hotter and may create an alternating current with the same frequency as the radiation itself.
• Different wavelengths of electromagnetic radiation have different effects on living cells. Some radiations mostly pass through soft tissue without being absorbed, some produce
heat, some may cause cancerous changes and some may kill cells. These effects depend on the type of radiation and the size of the dose.
Students should use their skills, knowledge and understanding of „How Science Works‟:
• to evaluate the possible hazards associated with the use of different types of electromagnetic radiation
• to evaluate methods to reduce exposure to different types of electromagnetic radiation.
Teaching suggestions
Activities

As mentioned in title, Brainiac has a good clip where 100 mobile phones are piled over an egg and then called to see if the combined heat
would cook the egg. Natch it doesn’t!
Selling the radio spectrum – Mobile phone companies actually paid over £22 billion for their 3G UK licences, nearly making some of them bankrupt. The government used some
of this to pay off debts from World War Two! Another large amount will be raised when the analogue TV bands are sold off. What do the students think should be done with this
money?
The allocation of the spectrum is now controlled by Ofcom and their web site contains a complete breakdown of the uses of the radio spectrum. Search their site for the „frequency
allocation table‟; it is a bit technical in parts, but it‟s interesting to see the varied uses of the frequencies.
A key scientific invention – By late in the war, radar had developed so much that a submarine could be detected at a range of several kilometres, even if it just popped up to
replenish oxygen supplies or receive radio orders. The survival rates of U-boat crew were very low in the last couple of years of the war. The Germans tried to develop a U-boat that
could stay under water for much longer, but the project was too late and the battle had already been lost. Once the convoy routes were secure, the build up to D-Day could begin.
You may like to look into „stealth‟ technology developed to reduce the radar signature of planes and some ships. If you are discussing these ideas, then make sure that the students do
The big switchover – Some areas of the UK have already switched entirely to digital transmissions, such as Llanstephan in Wales, as an experiment to see if it works well enough.
There are still problems with digital television; not all of the country is covered by the signal, and reception is poor in a number of hilly areas. Should these people be provided with
free satellite dishes? Should everybody else be given free „digiboxes‟ when the switchover comes? This could cost hundreds of millions of pounds. The students can find a map of
areas covered online or search by postcode; search for „freeview coverage‟.
Mobile phone hazards – You may have had a discussion about mobile phone hazards at the beginning of the chapter. If you have, you can briefly revisit the idea and see if any of
the students have changed any of their opinions in light of their new knowledge. The debate here could be more focused on the social aspects of mobile phone use: where should they
and where shouldn‟t they be allowed and the accidents that can happen when using them. There are many campaign sites available on the Internet, some with detailed information
and others with vague assertions. This evidence must be evaluated before being used in any debate.
Extension or homework
The poster activities can be carried out at home, as can the research for the phone debate. http://imagers.gsfc.nasa.gov/teachersite/wavstown.pdf
Information required for the debate on mobile phones and their masts is available on the Internet from a variety of sources. The students will need to evaluate the reliability of this
information based on the agendas of those producing the sites; from phone companies, the government and campaign groups. This is useful for teaching about societal influences,
required in the „How Science Works‟ section of the specification.

Learning styles
Kinaesthetic: Role-play of mobile phone debate.
Visual: Obtaining information on phone maps.
Auditory: Discussing a range of issues.
Interpersonal: Discussing and debating.
Intrapersonal: Evaluating evidence from Internet research.
How does radar work? The students can make a booklet or presentation explaining how radio waves can be used to detect objects. They can even look into ways of avoiding being
detected by radar, such as the common film tactic of „flying in below the radar‟.
AQA GCSE Science: P1b 6.1 Observing nuclear radiation
• The basic structure of an atom is a small central nucleus composed of protons and neutrons surrounded by electrons.
• Some substances give out radiation from the nuclei of their atoms all the time, whatever is done to them. These substances are said to be radioactive.
Learning Objectives              Teaching / Learning activities (including How Science Works)                                                      Teaching suggestions
Students should learn:                                                                                                                             • Learning styles
• The basic structure of an      Lesson structure                                                                                                  Kinaesthetic: Modelling the
atom.                            Starter                                                                                                           structure of an atom.
• That unstable nuclei decay     Seeing the invisible – How can we detect things that we cannot see? Ask students to come up with a list of        Visual: Observing demonstrations/
and emit invisible radiation     things that we cannot see and how we can detect their presence, e.g. air, infra-red radiation. (5–10 minutes)     computer animations and
when the structure of the        Atom – What does an atom look like? Ask the students to draw and label one before showing them our                simulations.
nucleus changes to become        current (nuclear) model. Does an atom really look like this? (5–10 minutes)                                       Auditory: Listening to descriptions
more stable.                     Atom models – Give the students a set of cut-out protons, neutrons and electrons                                  of nuclear processes.
• That this radiation can be     and ask them to make a model atom. (10 minutes)                                                                   Interpersonal: Discussing the
detected in a number of ways                                                                                                                       dangers of scientific research.
including by a GM tube.                                                                                                                            Intrapersonal: Evaluating safety
Main
precautions.
• Before carrying out any demonstrations involving radioactive material, make certain that you are familiar
with local handling rules. (See „Practical notes‟.)
• The students cannot handle
• Start by checking knowledge of atomic structure, protons, neutrons and electrons, as this is essential in
discussing isotopes later.
simulations on the GCSE Science
• You can then discuss the history of the discovery of radioactivity. You should point out that although the
CD allow them to explore ideas
initial discovery was accidental, the investigation into the cause was a thorough scientific one.
safely. These are an excellent way
• Marie Curie died aged 67 partly because of her work. Similar things happened with early researchers into
to visualise the behaviour of the
X-rays. This shows that even scientists under-estimate the hazards of their research.
particles and waves and to study
• Show the presence of radiation due to the sources by using a GM tube or spark detector. (See „Practical
absorption. They can also
support‟.)
demonstrate the half-life of
• Use the Interactive Simulation P1b 6.2 „Alpha, beta and gamma radiation‟ to show the different types of
materials, a process that is too
difficult to show with real
• Emphasise that nuclear radiation is caused by changes in the nucleus. You could link back to the difference
substances in class. However, it is
between X-rays (caused by electrons) and gamma rays (caused by the nucleus).
best to use these simulations
• You might ask the students to draw the nucleus of a couple of isotopes to check that they understand the
alongside real apparatus if possible,
term. If you do this, it is worth reminding them that the nucleus is really spherical; not just a disc. Show a
to show that the models are linked
model made of marbles stuck together; if one falls off, then attribute it to nuclear decay.
to physical reality. • If you do not
• Some students may like to know why the nucleus decays. The reason for the nucleus changing is linked to
want the student to get too close to
energy. The nucleus changes so that it has less energy; the parts that make it up have become more tightly
the sources, then you could connect
bound; this is yet another example of energy spreading out.
a small video camera to a data
projector to show the
Plenaries
demonstrations more clearly.
Isotope analysis – The students are given a list of isotopes to draw the structure of, or diagrams of nuclei for
them to describe. They could use a periodic table to help identify the element. (10 minutes)
Murder mystery – The body of a press photographer has been found in a sealed room, all of the film in her
camera has gone black even though it hasn‟t been used. Write a letter to the police explaining what you think
happened and how you know. (5–10 minutes)
It’s elementary – Give the students a list of recently discovered elements and see if
they can figure out what they are named after (Californium, Curium, Nobelium,
etc). What would the students call an element that they discovered? What symbol
would it have? (5 minutes)
Learning Outcomes                             Practical support
Most students should be able to:              Demonstrating radioactive sources safely
• Draw a diagram illustrating the structure   Radioactive sources can be used to demonstrate important aspects of this chapter, but there are important safety considerations to take
of an atom (nuclear model)                    into account. Your school should have a set of local rules that apply to the storage and handling of radioactive sources, and these should
• State what we mean by a „radioactive‟       inform you as to the ways to handle practical activities. You should make the students fully aware of the dangers associated with the
substance.                                    sources, but also emphasise that you will be handling them with great care and they are in no danger as long as they too follow sensible
• Describe ways in which radioactivity        procedures. You should discuss the reasons for the safety points below with the students:
can be detected.                              • Do not handle radioactive sources until you have had a training session from the school Radiation Protection Supervisor.
• Under no circumstances allow the students to handle the sources.
Some students should also be able to:         • Always minimise exposure; keep the sources in the storage container whenever they are not being used and only demonstrate with the
• Explain why some substances are             sources for the minimum time possible to get the concept across.
radioactive.                                  • Always handle the sources with tongs away from the trunk of your body to minimise exposure.
• Perform experiments in a large tray, so that if sources are dropped they do not roll and fall to the floor.
• Check all sources are returned to the storage container and storage facility before the end of the lesson.
Using a GM tube and ratemeter
The usual way of showing the presence of ionising radiation is by using a Geiger Müller tube and ratemeter. This has the advantage that
the count rate is proportional to the activity, and some of the students will be familiar with the device from films and television.
Equipment and materials required
Details
The operating voltage of the GM tube is usually 400V and this is usually provided by the ratemeter, but you may need an external
supply for tubes that connect to computers. Check with the manual if you still have it. Position the detector in the tray and switch it on.
Bring the sources close to the tube window and the ratemeter should count. If you can find a ratemeter that clicks, the demonstration is a
lot more fun.

Equipment
Geiger Müller tube
ratemeter (and possibly high voltage power supply)
large plastic tray
tongs
lab coat
Meter rule

Risk assessment
Make sure you speak with technicians for a full risk assessment when using radioactive samples.
AQA GCSE Science: P1b 6.2 Aplpha, beta and gamma radiation
• The characteristics and properties of the three main types of nuclear radiation emitted by radioactive sources: alpha particles, beta particles and gamma rays.
• The uses of, and the dangers associated with, each type of nuclear radiation. Students should use their skills, knowledge and understanding of „How Science Works‟:
• to evaluate the possible hazards associated with the use of different types of nuclear radiation
• to evaluate measures that can be taken to reduce exposure to nuclear radiations.
Learning Objectives               Teaching / Learning activities (including How Science Works)                                                         Teaching suggestions
Students should learn:                                                                                                                                 • Gifted and talented. Where do
• The different radiations       Lesson structure                                                                                                     the beta particles come from? The
have different penetrating        Starter                                                                                                              beta particles are high-energy
powers because they are           Magnetism – The students should be familiar with magnetic fields. Ask them to show their knowledge in a              electrons that come from the
absorbed by materials as they     diagram/mind map/spider diagram. (10 minutes)                                                                        nucleus, but there are no electrons
pass through.                     It’s all Greek to me – Scientists use a lot of symbols in their work. Discuss the reasons that scientists use        in the nucleus! The students need to
• The range in air is different   symbols for elements, equations, the names of things, etc. You might ask the students to list all of the             find an explanation of what is
for each type of radiation and    symbols that they know the meaning of; they know more than they think. (5–10 minutes)                                happening in the nucleus that is
that they are affected            This isn’t a Biology lesson! – Ask the students to draw and label the important parts of an animal cell. They        producing these electrons.
differently by electric and       should explain where the genetic information is stored. (5–10 minutes)                                               • Learning styles
magnetic fields.                                                                                                                                       Kinaesthetic: Modelling with
• Nuclear radiation is ionising   Main                                                                                                                 simulations.
and this damages living cells     • The Interactive Simulation P1b 6.2 „Alpha, beta and gamma radiation‟ show the different types of radiation         Visual: Observing demonstrations.
causing cancer or cell death.     coming from the nucleus. A simulated experiment allows students to test what different types of radiation            Auditory: Explaining effects of
• You may demonstrate the penetrating powers of radiations with the method set out in „Practical support‟.           Interpersonal: Discussion of
• The difference between alpha and beta particles and the electromagnetic wave nature of gamma should be             radiation.
emphasised.                                                                                                          Intrapersonal: Interpreting evidence
• Gamma radiation causes no change in the structure of the nucleus; it is really the nucleus dumping some            from demonstrations.
excess energy it didn‟t lose in a previous decay.
• The lack of charge on the gamma rays accounts for their higher penetrating power; they interact with
matter a lot less than alpha or beta.
• Depending on the structure of your course, the students will probably not have encountered the idea of
ionisation before. It is important that they grasp the concept of the radioactive particle stripping away
electrons from atoms and causing unwanted chemical reaction in cells.
• The main danger is that the cell will be damaged and reproduce out of control. Explain that this becomes
more likely the larger the dose of radiation, but that it is possible for a single damaged cell to cause cancer so
there is no minimum safe limit to radiation. We should therefore try to limit our exposure by keeping
sources safely away from our bodies.
• The students will look at the natural background radiation later, but some may have noticed the Geiger
counter clicking away even when there are no sources in the room.
Plenaries
Local rules – The students should make a poster or booklet explaining how your radioactive sources should
be stored and handled. (15–20 minutes)
Summary diagram – Can the students draw a single diagram that will summarise all of the information
from today? (10 minutes)
Protect and survive – What if one of the radioactive sources was dropped and lost? How would it be found
and what precautions would need to be taken during the search? (10 minutes)

Learning Outcomes                                                                              Practical support                                 Activities and extensions
Most students should be able to:                                                               Penetrating power                                 More detectors – There are other
• Describe the penetrating powers of the three radiations.                                     The techniques used on the previous spread        ways of detecting and analysing
• Describe the range in air of each type of radiation, their relative ionising power and how   can be expanded to show the penetrating           ionising radiation, including cloud
they are affected in a magnetic field.                                                         power of the three radiations. (Teacher           and bubble chambers and
• Evaluate which radiation is the most hazardous inside and outside of the human body.         demonstration only.)                              photographic films. The students
• Describe ways of reducing the hazards presented when handling radioactive substances.        Equipment and materials required                  could find out about these devices
Geiger Müller tube, ratemeter (and possibly       and why they are used. Which of
Some students should also be able to:                                                          high voltage power supply), large plastic tray,   the devices reveals most about the
• Explain why radiation is dangerous.                                                          tongs, radioactive sources, set of absorbers      radiation and in what circumstances
(paper, card, plastic, aluminium of various       are they used?
Details
Set the equipment up in the tray, as before,
but add a mount to position a source in place.
Between the source holder and detector
position a holder to hold the absorbers. Make
sure that the detector is less than 10 cm from
the source holder or the alpha particles will
not reach. Turn on the detector and then
mount an alpha emitter in the holder and note
the count rate. This function can be
performed by most meters, but you may have
to count for 20 seconds if not. Position a
paper absorber between the source and
detector and note the count rate. Test the beta
source with paper, plastic and then aluminium
plates. Test the gamma with aluminium and
AQA GCSE Science: P1b 6.3 Half-life
• The half-life of a radioactive substance is defined as „the time it takes for the number of parent atoms in a sample of the substance to halve‟ or „the time it takes for the count rate
from a sample of the substance to fall to half its initial level‟.

Learning Objectives                Teaching / Learning activities (including How Science Works)                                                        Teaching suggestions
Students should learn:                                                                                                                                 • Special needs. Students should be
• The activity of a radioactive   Lesson structure                                                                                                    provided with a results table with
source decreases with time         Starter                                                                                                             one set of results already filled in to
because the number of              An exponential decay puzzle – A farmer has a warehouse with two million corn cobs in it. Every day he               help explain the idea.
unstable nuclei is decreasing.     sells exactly half of his remaining stock. How long before he has sold every last nugget of corn? (5–10             • Learning styles
• The half-life of a source is a   minutes)                                                                                                            Kinaesthetic: Practical dice activity.
measure of how long it takes       An exponential growth puzzle – A philosopher places a grain of rice on the first square of a chess board,           Visual: Observing and presenting
for the activity of a source to    two on the next, four on the next and so on. How many go on the last (sixty-fourth) square? (5–10 minutes)          evidence.
reach half of its initial value.   The big time – Give the students a set of events and time intervals, ask them to put them in order of               Auditory: Explaining the evidence.
duration. Examples include a second, a century, an epoch, the duration of a lesson and the time a match takes       Interpersonal: Evaluating quality of
to burn. (10 minutes)                                                                                               results.
Intrapersonal: Interpreting
Main                                                                                                                evidence.
• Begin by discussing the term „isotope‟. The students should be becoming familiar with the structure of the        • ICT link-up
atoms and should quickly grasp that the number of neutrons may vary.                                                • The half-life of most materials
• „Parent‟ and „daughter‟ are important terms also. You could show a nuclear decay equation (or a simplified        available to high schools is too long
one) to get these terms across.                                                                                     to measure in class. A simulation of
• The rolling dice decay model is an enjoyable experiment, but it can take a bit of time. To improve the            decay is the best way to approach
average values the groups can share data and this will lead to a more precise half-life.                            this topic.
• At the end of the experiment, make sure that the students understand that the dice represented nuclei and         • Half-lives can be modelled in
removing them represented decay.                                                                                    detail using a spreadsheet. The
• They should have a reasonable understanding that the pattern is the same each time, even though we do not         students could enter their results
know exactly which of the dice decays each time.                                                                    and plot the graph. For the more
• If you feel like being a bit „all knowing‟, seal the answer in an envelope in advance and stick it to the board   mathematically inclined, the
in plain sight. Then „reveal‟ it at the end, which allows you to discuss the fact that we can accurately model      spreadsheet can calculate a function
random behaviour using mathematics.                                                                                 of the decay curve which should be
• The experiment lends itself well to the ideas of repeating to improve reliability, but can also be used to        y=y0 e-(1/6)x if results are ideal.
explain that statistics work best on very large samples so the more dice the better the fit. (This relates to
„Ideas of reliability of data‟ in „How Science Works‟.)
• There is also opportunity to develop or assess graph plotting skills along with drawing lines of best fit.
(This relates to „Presenting data‟ in „How Science Works‟.)
• You can discuss what happens to the „count rate‟ after each roll. The number of dice eliminated represents
this and this rate should decrease as the number of surviving dice falls. This gives the students a decent
understanding of why the count rate falls as time goes on.

Plenaries
Careful! You can have your eye out with that! – An archaeologist claims to have found the arrow that
killed King Harold in 1066. Can the students explain how a scientist would try to check this claim? (10
minutes)
Coin toss – If I have 120 coins and toss them all, removing all of the heads after each toss, how many tosses
until I should only have 15 left? [3 tosses.] (5 minutes)
Activity and decay – Show the students a graph with three decay curves on them. Can they identify which
has the longest half-life and which is the most active source? (5 minutes)

Learning Outcomes                                                                     Practical support                                             Activities and extensions
Most students should be able to:                                                      Radioactive dice                                              Roll the dice – Starting with the
• Define the term half-life in relation to the activity of a radioactive source.      This is a simple model of the randomness of radioactive       basic six-sided dice experiment, the
• Determine the half-life of a source from a graph or table of data.                  decay and how to find the half-life.                          students could investigate what
Equipment and materials required                              would happen if a different set of
For each group: a set of 59 identical six-sided cubes and     dice were used. Dice with 4, 8, 10,
one cube of a different colour. The dice should have a dot    12 and 20 sides are available from
on one face only. (You can use more or less dice              gaming shops, and will produce
depending on how many you have, but 60 works well.)           similar exponential decay curves
Details                                                       but with different half-lives.
The students roll the full set of dice, and after each roll
they remove the dice that landed showing a spot. They
record the number of dice „surviving‟ and then roll only
these dice, and so on. They continue this process of
elimination for 20 rolls, or until no dice survives. During
this, they should also note down when the special dice
lands spot up causing it to be removed. If time permits,
they repeat this process and calculate an average number
of dice remaining after each roll. Plotting a graph of the
number of dice remaining (y-axis) against roll number (x-
axis) reveals that the dice behave like decaying atoms and
a half-life can be calculated; this should be 4.16 rolls.
The single dice should show that the process is random; it
is impossible to predict when any individual dice will be
eliminated. For some groups, it will be removed after the
first roll and for others it will survive until the end.
AQA GCSE Science: P1b 6.4 Radioactivity at work
• The uses of, and the dangers associated with, each type of nuclear radiation. Students should use their skills, knowledge and understanding of „How Science Works‟:
• to evaluate the possible hazards associated with the use of different types of nuclear radiation
• to evaluate measures that can be taken to reduce exposure to nuclear radiations
• to evaluate the appropriateness of radioactive sources for particular uses, including as tracers, in terms of the type(s) of radiation emitted and their half-lives.
Learning Objectives              Teaching / Learning activities (including How Science Works)                                                       Teaching suggestions
Students should learn:                                                                                                                              • Special needs. Provide a partially
• That radioactive sources      Lesson structure                                                                                                   completed flow chart for the
have a number of uses            Starter                                                                                                            operation of the foil press.
including thickness              Radiation misconceptions – The students will have seen a range of films in which radioactive materials             • Gifted and talented. Very large
measurement, medical tracing     have caused strange effects. Get them to list all of the things they think radioactivity can do, and then go       numbers of radioactive particles are
and determining the age of       through them deciding if they are true or false. (5–10 minutes)                                                    produced in nuclear reactors. How
materials.                       Just how thick? – Ask the students to measure the thickness of a sheet of paper. Can they find out if all of       are these particles contained and are
the sheets are the same thickness? How? (5 minutes)                                                                there any that escape into the
PhotoPLUS – View and discuss the PhotoPLUS on „Radioactive issues‟, available on the GCSE Science                  environment? The students may
CD. (10 minutes)                                                                                                   find out about neutrons and
neutrinos.
Main                                                                                                               • Learning styles
• Using radioactivity to determine the thickness of a material is a fairly straightforward idea; you can link it   Kinaesthetic: Researching into
to the idea of light being absorbed by paper. How many sheets of white paper will stop all light passing           dating techniques.
through it?                                                                                                        Visual: Observing absorption
• The function of the foil press can best be shown as a flow chart with terms like: „Is too much radiation         demonstration.
getting through?‟→„Open up rollers a bit.‟                                                                         Auditory: Reading aloud
• Demonstrate that the thicker a material is the less beta radiation passes through. This could be a quick         information.
demonstration as in „Practical support‟, or you could look into it in more depth.                                  Interpersonal: Discussing uses of
• When discussing radioactive tracers, you may be able to find a video clip of a tracer being used in the body     radioactivity.
to find a blood vessel blockage. (For example, search an image bank for „radioactive tracer‟.)                      Intrapersonal: Understanding
• The students should be made aware that the tracer must be picked for the job based on a range of factors,        radiometric dating techniques.
including the type of radiation it emits (gamma) and its biochemical properties, i.e. will it build up in the      • ICT link-up. A simulation of the
organ we want it to?                                                                                               absorption of beta particles by
• There are isotopes suitable for a wide range of medical studies, some of which are artificially generated in     various resources is available. The
nuclear reactors.                                                                                                  students can find out for themselves
• You may want to talk about tracers used to find gas leaks and monitor the path of underground rivers.            how the particles are absorbed by
These too are carefully chosen.                                                                                    different materials.
• Carbon dating is only useful over a certain range of times and the materials must be organic. The limit is
about 50 000 years, which is good enough for all recorded human history.
• It also needs to be calibrated against objects of known ages; ancient trees are handy for this. Ask the
students how we know the age of these trees.
• Uranium dating is generally used to date rocks and is part of the evidence for the Earth being 4.5 billion
years old.
• There are some assumptions that are made with dating processes and you may wish to discuss these with
the students. Do the levels of carbon-14 remain constant in the atmosphere? Is there any other way of lead
being produced in rocks?

Plenaries
The dating game – Give the students a set of cards of historical events and a set of „radioactive activities‟
that have been measured for artefacts from these events. Ask the students to match them up. (5 minutes)
The right isotope – Can the students match the isotope to the job it is used for? Give them a list of isotopes,
the type of emitter they are and their half lives and see if the students can decide what they would be useful
for. (10 minutes)
expounding the virtues of radioactive material. (15–20 minutes)

Learning Outcomes                                                                                Practical support
Most students should be able to:                                                                 Demonstrating absorption
• Describe how a beta source can be used to measure the thickness of a material like             See local rules for handling radioactive sources. It is possible to show how
aluminium foil.                                                                                  radioactivity can be used to measure the thickness of materials. (Teacher
• Describe how radioactive traces are used in medical analysis.                                  demonstration only.)
• Describe how radioactive isotopes can be used to determine the age of a rock or organic        Equipment and materials required
material.                                                                                        GM tube and rate meter, set of aluminium absorbers, beta source, tongs.
Details
Some students should also be able to:                                                            Mount the GM tube and absorber holder in line with the source holder. Position the
• Evaluate the properties of a radioactive isotope to determine why it would make a good         source carefully and record the count rate (or take a count over 30 seconds). Test the
medical tracer.                                                                                  aluminium absorbers one at a time, noting the decreasing count rate as the thickness
• Find the age of an organic sample from date presented to them.                                 of the aluminium increases.
You may wish to get the students to plot a graph of count rate against absorber
thickness to determine how much aluminium is required to reduce the count to half
of the original value. This half-value thickness is an important concept for absorption
of gamma rays at Advanced level.
AQA GCSE Science: P1b 6.5 Radioactivity issues
Substantive content that can be revisited in this spread:
• The uses of, and the dangers associated with, each type of nuclear radiation.
Students should use their skills, knowledge and understanding of „How Science Works‟:
• to evaluate the possible hazards associated with the use of different types of nuclear radiation
• to evaluate measures that can be taken to reduce exposure to nuclear radiations
• to evaluate the appropriateness of radioactive sources for particular uses, including as tracers, in terms of the type of radiation emitted and their half-lives.
Teaching suggestions
Activities
Nuclear waste – Extensive details of the handling and storage of nuclear waste can be found from the Internet. A basic search for „nuclear waste‟ will yield sites from BNFL,
Greenpeace and a range of other pro and anti nuclear organisations.
Interestingly the device used to remotely handle dangerous materials is called a „waldo‟. These were thought up by the science fiction author Robert Heinlein, before they were
actually turned into reality.
Chernobyl – You may have had a debate about Chernobyl and nuclear reactor safety during a previous section. If not, then the students are now better informed and a debate would
be very useful. The debate should take into account the need to reduce global warming, the storage of waste produced and the safety record of nuclear power stations.
Radioactivity all around us – The students will most likely think of radioactivity being an unnatural phenomenon, and it is important to get across the idea that most of the dose that
they receive is from natural sources. You can measure the amount of background radiation during the lesson. Radon gas is a major cause of lung cancer in the UK, with estimates of
deaths at around 2500 per year. This compares to about 25 000 due to smoking. The gas is released from igneous rocks; (link back to geothermal energy) and the students may be
interested in the areas that contain most of these rocks, such as Devon and Cornwall. Further information can be found from the Health Protection Agency (www.hpa.gov.uk) where
radon detectors can be purchased. Shouldn‟t these be free?
Radioactivity on the move – This is an excellent opportunity to discuss the safety of radioactive material. Ask the students to list a list of safety precautions that they would impose
when moving nuclear material by rail. Search the Internet for „nuclear container test‟ to find video of a nuclear container being tested in a crash. They should also be able to find
information about the ships that are used to transport material. How are these designed and protected?
In the „Radioactivity on the move‟ or „Nuclear waste‟ activities, the groups can present their evidence as a slide show. This would allow them to use information and images from the
Internet easily to support their case.
Learning styles
Kinaesthetic: Researching further information.
Visual: Obtaining and presenting information from the Internet.
Auditory: Explaining how radioactive material is kept safe.
Intrapersonal: Considering safety precautions used when handling materials.
AQA GCSE Science: P1b 7.1 How big is the universe?
• There is a red shift in light observed from most distant galaxies. The further away galaxies are the bigger the red shift.
• How the observed red shift provides evidence that the Universe is expanding and supports the „Big Bang‟ theory (that the Universe began from a very small initial point).
Learning Objectives               Teaching / Learning activities (including How Science Works)                                                    Teaching suggestions
Students should learn:                                                                                                                            • Learning styles
• The Universe is a vast         Lesson structure                                                                                                Kinaesthetic: Matching spectra cards.
collection of billions of         Starter                                                                                                         Visual: Imagining the expansion of
galaxies each containing          How many stars? – Give the class estimates on the number of stars in a galaxy                                   the Universe.
millions of stars.                and the number of galaxies, and ask them to work out how many stars they could                                  Auditory: Explaining the evidence for
• The velocity of distant                                                                                                                         expansion.
galaxies can be measured by       have each if they shared them out between the class. (5 minutes) (1022 to 1024                                  Interpersonal: Discussing and
analysis of the red shifting of   stars in the Universe)                                                                                          evaluating the evidence.
light from those galaxies.        Our star – Get the students to list the reasons why the Sun is important to life on Earth. What does it         Intrapersonal: Appreciating the model
• The evidence gained from        provide the Earth with? (5–10 minutes)                                                                          of the expanding Universe.
red shift analysis proves that    Stars and planets – Give the students sets of cards describing the properties and behaviours of stars and       • Gifted and talented
the Universe is expanding and     planets, and ask them to sort them into two piles. (5–10 minutes)                                               Emission spectra
is of finite age.                                                                                                                                 If you have a set of gas emission
Main                                                                                                            spectrum tubes, you can demonstrate
• You might like to ask the students why there are no photographs of the complete Milky Way                     the emission spectra of different hot
Equipment.                        galaxy; they should realise that we could never get a probe to sufficient distance.                             gases. With a suitable diffraction
Calculators                       • If you want to show a model galaxy, try using a blank CD with a small bulge of Plasticine in the centre.      grating and spectroscope, you can
Large balloon                     You can draw the spiral arms on the label. It‟s about the right proportions (according to NASA). We are         clearly see the distinct lines produced
on the western spiral arm about 1cm from the rim.                                                               by different elements. If you don‟t
• You can then show the separation of galaxies. Our neighbour Andromeda would be about 1m away on               have a spectroscope, you can still
this scale.                                                                                                     show the different colours from
• A Doppler shift for sound (a similar effect to the red shift) can be demonstrated with a tube and a funnel.   different elements. (You may also
The students may be familiar with the effect when hearing sirens on cars passing by.                            wish to link this idea to the flame
• It is useful to show the students simple samples of absorption spectra to show what these lines would         tests for the applied science units.)
look like. They can then show the effect of shifting the lines to the red part of the spectrum. See Attatched   • ICT link-up. Why do scientists
powerpoint.                                                                                                     need more and more powerful
• The idea of an expanding universe that has no centre is a bit strange. The closest simple analogy is the      computers? Simulations of galaxies
surface of an expanding balloon. It is worth showing this: blow up a balloon with galaxies drawn on its         smashing together may look nice, but
surface and they all move further apart from one another and none of them are in the middle.                    it takes a lot of computing power to
• The Universe is a bit like this; but it isn‟t expanding „into‟ anything as it is expanding in three           work out when a billion stars meet
dimensions, not two like the surface of the balloon.                                                            another billion stars. Many of the
If pupils question this explain that the universe is expanding at the speed of light, and since                 simulations on-line have been carried
nothing can move faster it is impossible to catch up with „the edge‟.                                           out by „supercomputers‟ thousands of
times more powerful than a simple
PC. There is a PhotoPLUS, P1b 7.2
Plenaries                                                                                                       „Big bang‟, available on the GCSE
Space is big – Give the students a list of distances and ask them to put them in order                          Science CD. This could be used next
(e.g. Earth to Moon, Earth to Sun . . . Milky Way to Andromeda). (5 minutes)                                    lesson.
True or false – Give the students a set of „facts‟ about galaxies and the Universe, and ask them to say if
they are true or false. (5–10 minutes)
Corrections – Give the students a paragraph full of mistakes describing the expansion of the Universe.
They must correct every mistake. (5–10 minutes)

Learning Outcomes                                                                                Activities and extensions
Most students should be able to:                                                                 Doppler and sound
• State that the Universe contains a vast number of galaxies and stars.                          A 1.5 m length of hosepipe is ideal for this, but other tubes work reasonably. You
• Explain that red shift evidence shows that the Universe is expanding.                          need to stick a large funnel (firmly) in one end and then blow down the other, while
swinging the tube above your head. The pitch (and so frequency and wavelength of
Links:                                                                                           the sound) changes as it swings towards and away from the students. When it is
moving away, the wavelength is increased so the sound is lower pitched and vice
Expanding Universe powerpoint                                                                    versa.
Matching spectra
Doppler effect animation: http://www.freezeray.com/flashFiles/DopplerEffect.htm                  Can the students discover what elements are present in real stellar spectra? Give the
And                                                                                              students a card showing the absorption spectrum of the Sun and a set of spectra for
http://molebash.com/doppler/home.htm                                                             different elements, some of which are present in the Sun; ask the students to work
out which ones match. Make sure the cards are printed to the same scale though.
Andromeda ascendant
The Andromeda galaxy is one of our nearest galactic neighbours and it is getting
nearer all the time. It‟s moving towards us at about half a million kilometres per hour
and will eventually collide in three to four billion years‟ time. The students could
look into the possible outcomes of this collision, and collisions on this scale
generally. There are numerous excellent computer simulations, and Hubble Space
Telescope images of real collisions, available on the Internet.
AQA GCSE Science: P1b 7.2 In the beginning there was nothing...which exploded!
• How the observed red shift provides evidence that the Universe is expanding and supports the „Big Bang‟ theory (that the Universe began from a very small initial point).

Learning Objectives              Teaching / Learning activities (including How Science Works)                                                     Teaching suggestions
Students should learn:                                                                                                                            • Gifted and talented. Just how
• The Universe is thought to     Lesson structure                                                                                                 small is „small‟? These students
have begun in a dramatic         Starter                                                                                                          may wish to look into the
event called the Big Bang.       Bang! – Show a video clip of a large explosion and ask students to describe dramatically what is going on.       concept of singularities: objects
• The expansion of the           (5 minutes)
Universe supports the Big        Heat death – Remind students that all energy transfers lead to energy being wasted as heat. Ask them to
of zero volume and infinite
Bang theory.                     describe what will happen when all of the energy the Universe started with is wasted. (5 minutes)                density; it is from one of these
• The cosmic microwave           Your history – Give the students a list of historical events reaching back through                               that the Universe is thought to
background radiation is a                                                                                                                         have originated. The ideas are
human history, and then to the formation of the Earth. Ask them to put the events
primary piece of evidence                                                                                                                         closely linked to black holes,
leading to this conclusion.      in order. (15 minutes)                                                                                           which the students will study
later in the next topic; you may
Main
Equipment.                       • This lesson is all about big ideas and how scientists have to provide evidence for them. (It is ideal for      wish to leave this until then and
NA                               teaching aspects of „How Science Works‟.)                                                                        link the two ideas together.
• Many students may ask what was before the Big Bang. The best approach is to talk about the meaning of          • Learning styles
„before‟. As scientists believe that time only started with the Big Bang there was no time before it, so it is   Kinaesthetic: Research into
meaningless to ask questions about what happened. A PhotoPLUS, P1b 7.2 „Big bang‟, is available on the           previous ideas about the Universe.
GCSE Science CD to help students explore the idea.                                                               Visual: Imagining the Big Bang.
• Students may also be a bit confused by the term „explosion‟. The Big Bang is better described as a sudden      Auditory: Hearing the description
expansion and the production of a lot of energy. As the Universe continues to expand, this energy gets more      of the end of the Universe.
and more dissipated and so the Universe cools down.                                                              Interpersonal: Discussing the origin
• The main thrust of the lesson is to explain to the students that an idea like the Big Bang needs to            of the Universe.
have evidence before it is accepted by scientists. It is not enough to come up with the best                     Intrapersonal: Considering the
evidence for the Big Bang model.
sounding explanations. This links to the „fundamental ideas‟ section of „How Science Works‟.                     • ICT link-up. There are several
• Those that did not accept the theory were right to, until they were given evidence of the cosmic background
web sites explaining the Big Bang
radiation. They should then accept the new model, or come up with an alternative explanation that takes the
and theories about possible ends to
new evidence into account.
the Universe. Some are a bit
• Changes to ideas like this are important to science; the students need to know that scientists will analyse
technical, but students may wish to
new ideas and accept them if they explain the evidence better than the old ideas. This process ensures that
find out more from them. Search at
scientific knowledge develops and becomes a better description of the Universe.
www.nasa.gov or www.bbc.co.uk.
• You should also point out that recent discoveries, such as the possible speeding up of the expansion, will
also have to be explained by scientists over the coming years; we do not have a complete description of the
Universe and may never have.
• Conditions in the very early Universe were very different than they are now. The temperatures were so
high that atoms could not exist, and even protons and neutrons could not form.
• The cosmic background is a result of this stretching of the wavelength; you can link this to the idea of red
shift but the two processes are a bit different.
• The end of the Universe is still open to debate, and students should not worry too much about it.
We have a few billion years to go before a „Big Crunch‟ or a „Big Yawn‟.

Plenaries
Better Big Bang – The term „Big Bang‟ is not a very good one to describe the beginning of the Universe.
Can the students come up with a better term for it? (5 minutes)
Can science answer everything? – Have a brief debate with the students about the
limits of scientific understanding. Can all questions be answered by scientific research?
(10 minutes)

Learning Outcomes                                                                                Activities and extensions
Most students should be able to:                                                                 A steady state
• Describe the Big Bang as the event that generated the Universe.                                Some scientists heartily resisted the idea of a „Big Bang‟ and expanding Universe.
• Describe the evidence for the expansion of the Universe and how it supports the Big Bang       The students could find out who these where and what their objections were. Do all
theory.                                                                                          scientists agree on the Big Bang model now?
• State the evidence for this conclusion.                                                        Improving evidence
Ever since the discovery of the cosmic microwave background radiation, scientists
Some students should also be able to:                                                            have been trying to find improved ways of measuring it so that they can find out the
• Describe possible scenarios for the destiny of the Universe.                                   structure of the early Universe. The students can find out how satellites, including
the COBE mentioned in the Student Book, have been used to map the radiations and
find variations in it. There are several satellites that have been used, or are due for
launch in the coming years, all with dedicated web sites.
AQA GCSE Science: P1b 7.3 Milky way, comets and Pluto. More than a choc, shops and a dog?
• Observations of the solar system and the galaxies in the Universe can be carried out on the Earth or from space.
• Observations are made with telescopes that may detect visible light or other electromagnetic radiations, such as radio waves or X-rays.
Students should use their skills, knowledge and understanding of „How Science Works‟:
• to compare and contrast the particular advantages and disadvantages of using different types of telescope on Earth and in space to make observations on and deductions about the
Universe.
Learning Objectives              Teaching / Learning activities (including How Science Works)                                                        Teaching suggestions
Students should learn:                                                                                                                               • Gifted and talented. What is a
• A range of objects can be     Lesson structure                                                                                                    „black hole‟? The students can find
observed from the surface of     Starter                                                                                                             out about how these are formed and
the Earth and from orbit         What’s out there? – The students should list all of the different types of object that can be seen in space         how they behave. Will black holes
around it.                       from the Earth‟s surface with the naked eye, and perhaps draw what they look like. (5–10 minutes)                   eat up our entire galaxy one day in
• The atmosphere absorbs         Astronomical question loop – A chain of questions and answers about objects in the solar system. (5–10              the distant future?
some regions of the EM           minutes)                                                                                                            • Learning styles
spectrum and so prevents us      Shoddy solar system – Give the students a set of incorrect facts about the solar system                             Kinaesthetic: Making and using
from observing these regions     and ask them to correct them. (5 minutes) See Links                                                                 telescopes.
from the surface of the Earth.                                                                                                                       Visual: Observing astronomical
• Satellites above the                                                                                                                               images.
Main
atmosphere can be used to                                                                                                                            Interpersonal: Discussing the
• This is a fairly visual topic and benefits a lot from the use of images. Try to find some good
detect a larger range of EM                                                                                                                          advantages of space-based
waves, free from atmospheric     slides of all of the objects mentioned in the spread to show the students when they come up.                        telescopes.
distortions.                     There are many good sources of amazing images and animations. (Search at www.nasa.gov or                            • ICT link-up. Students can view
www.bbc.co.uk.                                                                                                      the PhotoPLUS, P1b 7.3 „Looking
Would help to have textbooks available for this and the following lesson, hence the book box.                       into space‟ in this lesson.
Equipment.                       • The students should be aware of comets from Key Stage 3. It is interesting to show them some historical
incorrect facts wsheet           comet events: perhaps the Bayeux tapestry or the Shoemaker Levy 9 and Jupiter collisions.
http://www.windows.ucar.edu/tour/link=/comets/comet_model_interactive.html very good site for showing
the path of comets, speed and their tails.
• There will probably be a discussion about what will happen if a comet or meteor hits the Earth about now.
You can deal with this now or in the next spread later; have a look there for more information.
• If you are working in a large town or city, some students will not have been able to see the full detail of the
Milky Way crossing the sky; it is well worth showing them just how many stars are out there.
• Try building the simple telescopes; the students may improve on the basic design.
• Link radio telescopes back to their understanding of the electromagnetic spectrum. Discuss that the
telescopes have to be very large because radio waves carry a lot less energy than visible light.
• When discussing satellites, point out that the main benefit is that they are above the atmosphere. The
atmosphere blocks quite a lot of the electromagnetic spectrum, so we would not be able to look at objects
that emit in these regions from the Earth‟s surface.
Interesting point for discussion about Plutos demotion to being a plannetoid. Possible pro and con
argument!

Plenaries
Jeopardy – Students have to think up questions about a list of astronomical objects
and terms. (10 minutes)
Comet legends – Comets are often associated with bad luck or major events. Can the students come up with
a comet legend about where they come from? (10 minutes)
It’s life Jim – Is there life „out there‟? Discuss the sort of things we should be looking for to find evidence
of alien life. (5–10 minutes)

NB: Next lesson requires a computer room to be booked

Learning Outcomes                                                                                Practical support
Most students should be able to:                                                                 Making astronomical telescopes
• List a range of commonly observed space objects and the equipment that is required to see      Simple telescopes are easy to build, but fiddly to use.
them clearly.                                                                                    Equipment and materials required
• Explain why it is not possible to monitor all EM waves from space at the surface of the        Metre rulers, 50cm and 5cm focal length converging lenses, some 75 cm lenses,
Earth.                                                                                           Plasticine.
Details
Some students should also be able to:                                                            Mount the 5cm lens at one end of the ruler and the 50cm lens 55cm along the ruler
• Describe the range of EM waves that can and cannot penetrate the Earth‟s atmosphere.           using Plasticine. The students look through the fatter (5cm) eyepiece lens and if they
• Describe the types of objects that produce gamma rays and infra-red radiation in space.        have aligned the lenses fairly straight, they should see an image. The image should
be magnified by a factor of five, but will only show a small part of what the
Links:                                                                                           telescope is pointed at. The students should think about how they would be able to
get a larger image and think up some ideas about improving magnification. Try the
Sol System errors                                                                                combination of 5cm and 75cm positioned 80cm apart.
www.nasa.gov                                                                                     Improving telescopes
http://www.bbc.co.uk/science/space/solarsystem/index.shtml                                       Once the students have explored basic telescopes, you could ask them to design
www.brainpop.com                                                                                 improved models. Perhaps they could think of sturdier ways of mounting the lenses.
Some students may try to think of ways of getting the image the right way up; they
could research „terrestrial telescopes‟.
Armageddon?
Should we be designing anti-comet and anti-asteroid measures? What can be done
and would it work? The students could produce a report on the feasibility and
usefulness of this idea. They would need to find out about the actual odds of an
impact and how much damage it would cause.
AQA GCSE Science: P1b 7.4 Looking into the unknown
Candidates should know and understand:
• Observations of the solar system and the galaxies in the Universe can be carried out on the Earth or from space.
• Observations are made with telescopes that may detect visible light or other electromagnetic radiations, such as radio waves or X-rays.
Students should use their skills, knowledge and understanding of „How Science Works‟:
• to compare and contrast the particular advantages and disadvantages of using different types of telescope on Earth and in space, to make observations on and deductions about the
Universe.
Teaching suggestions
Activities

I would suggest giving pupils a series of questions that require research on their part to answer. See Webquest in links for examples.

A short history of the Universe – The students should be able to find several web sites describing the early stages of the Universe. Many of these will be overly technical, but they
should get the general idea that the Universe was very different than it is now: atoms did not exist and light could not travel. The students should extend their timeline into the current
era, adding on information about the formation of our solar system and possibly even life on Earth. For what fraction of the life of the Universe has humans existed?

Galileo – There are many resources about Galileo Galilei and the students should prepare this information before the trial. You should be able to find transcripts from the trial, the
charges, verdict and the recantation of the „heretical‟ ideas by Galileo himself.

Mars Blog – The difficulties in getting to Mars in the first place should not be under-estimated. Ask the students to find out what resources would have to be taken for the trip and
how long it would take with current technology. They should be able to find a lot of information about the surface of Mars, as several probes have visited recently.

Space invaders! – The odds of being killed in an event like an asteroid impact lie between 1 in 20 000 and 1 in 1 000 000 000 000 depending on the information source. This should
reassure the students of their safety; although the dinosaurs may disagree. Even though an impact is unlikely, the damage would be tremendous – as the students will be aware of
from a range of films and television programmes. Some sources claim that we are „overdue‟ an impact: this is a misunderstanding of statistics that you may wish to correct. The fact
that we have not had an impact in a long time does not increase the chance of one occurring next year or the year after. The chance is the same (very small) each year.

Some interesting impacts worth talking about are the Chicxulub „Dinosaur killer‟ that hit the Yucatan peninsula 65 million years ago; the Barringer meteor crater in Arizona and the
mysterious Tunguska impact. There are many web sites dedicated to meteor impacts. Search at www.nasa.gov or www.bbc.co.uk.

SETI – SETI has an interesting web site (www.seti.org) with a great deal of information about their activities. It also has detail of the „Drake Equation‟ mentioned in the „Gifted and
talented‟.

Extension or homework
The students can visit the SETI site at home and may like to become involved with the search by joining the SETI@home project. With this, they can get their home computer to
analyse signals and perhaps discover alien life for themselves.
Students can analyse the odds of discovering alien life in the Universe with online versions of the Drake equation. Search the Internet for „Drake equation‟. They can change the odds
of each of the parameters and see how many intelligent species are predicted to be in our galaxy.

Teaching assistant
Your teaching assistant can be very helpful in the recording of discussions or helping to generate ideas in group work. They may also be of assistance with the construction of the
telescopes.

Learning styles
Kinaesthetic: Constructing telescopes (if not done in previous lesson).
Visual: Imagining life on Mars.
Auditory: Explaining their ideas.
Interpersonal: Debating the treatment of Galileo.
Intrapersonal: Writing a report about asteroid impacts.