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					Ch 1.3        Scientific Methods

Investigation & Experimentation Standards
1: a, b, c, d, e & g, j, k, l, & n
Scientific progress is made by
asking meaningful questions and
conducting careful
investigations. As a basis for
understanding this concept and
addressing the content
students should develop their
own questions and perform
investigations. Students will:
a.   Select and use appropriate tools and technology (such
     as computer-linked probes, spreadsheets, and
     graphing calculators) to perform tests, collect data,
b.   analyze relationships, and display data.
c.   Identify and communicate sources of unavoidable
     experimental error.
d.   Identify possible reasons for inconsistent results, such
     as sources of error or uncontrolled conditions.
e.   Formulate explanations by using logic and evidence.
f.   Solve scientific problems by using quadratic equations
     and simple trigonometric, exponential, and logarithmic
     functions.
g.   Distinguish between hypothesis and theory as
     scientific terms.
h.   Recognize the usefulness and limitations of models
     and theories as scientific representations of reality.
h. Read and interpret topographic and geologic maps.
i. Analyze the locations, sequences, or time intervals that are
characteristic of natural phenomena (e.g., relative ages of rocks,
locations of planets over time, and succession of species in an
ecosystem).
j. Recognize the issues of statistical variability and the need for controlled
tests.
k. Recognize the cumulative nature of scientific evidence.
l. Analyze situations and solve problems that require combining and
applying concepts from more than one area of science.
m. Investigate a science-based societal issue by researching the
literature, analyzing data, and communicating the findings. Examples of
issues include irradiation of food, cloning of animals by somatic cell
nuclear transfer, choice of energy sources, and land and water use
decisions in California.
n. Know that when an observation does not agree with an accepted
scientific theory, the observation is sometimes mistaken or fraudulent
(e.g., the Piltdown Man fossil or unidentified flying objects) and that the
theory is sometimes wrong (e.g., the Ptolemaic model of the movement of
the Sun, Moon, and planets).
          The word science means “to know.”


 What tool do scientists have that allows them to “know” about
  the physical world in a way that is different than, let’s say…
  philosophy?

 Science is limited to the world of:
  1.   Repeatable observations
  2.   Testable hypothesis

 A: THE SCIENTIFIC METHOD OF EXPERIMENTATION

 Let’s review the steps… write them down.
             Steps of the Scientific Method
1.       Observation- use senses to perceive object or events
2.       Ask Questions-
3.       Collect & organize data- longest phase of investigation
           use specific tools ex. microscope to observe directly or indirectly (voltmeter)
           quantitative (measured in numbers)
           Sampling (a small part represents an entire population)

4.       Hypothesize- a testable explanation that explains the observations
         and predicts the outcome
           Prediction posed as “if___ then___” statement.
           Inferences use logic and prior knowledge to make sense of the data
            collected and predict the result of a well-designed experiment.

5.       Experiment- testing a hypothesis under controlled conditions-
         comparison between control group & experimental group
6.       Draw conclusions
7.       Ask new questions
8.       Design new experiment (repeat & refine)
            How to write a Lab Report:
       (this mirrors the scientific method )
1.   Title

2.   Introduction (observations, background info, purpose of
     experiment)

3.   Hypothesis (is a prediction)

4.   Materials & Methods (explain the experiment)

5.   Results (tables, graphs- quantitative/qualitative)

6.   Discussion (analysis of results, misatkes?, conclusion,
     next experiment)
What are the elements of an
 excellent experiment???
              What are the elements of an
               excellent experiment???
1.       Control the variables (variables are any factors influencing the
         results of your experiment- keep them CONSTANT).
2.       Have a large sample size of test subjects &/OR repeat your
         experiment to counter unavoidable experimental error.
3.       Have a control group to compare your experimental group to so
         you see magnitude of the results.
4.       Change only ONE variable between these groups while holding
         all others constant. =‘s the INDEPENDENT VARIABLE
5.       Obtain quantitative data (when possible) and use appropriate
         tools for measurement
          Ex. pH meter, volt meter, microscope, ruler, scale, geiger counter.

6.       Organize collected data- measured results = DEPENDENT
         VARIABLE in a data table then show as a graph.
A controlled experiment is a comparison of two or
more groups with only one difference in variables
   between the groups when you set up your
                   experiment.


      CONTROL GROUP          EXPERIMENTAL GROUP


 1.   Soil              1.   Soil
 2.   Sunlight          2.   Sunlight
 3.   H2O               3.   H2O
 4.   CO2               4.   CO2
 5.   O2                5.   O2
 6.   Real trees        6.   Artificial trees
The difference between the groups is called
      the INDEPENDENT VARIABLE

  IT IS THE AGENT OF CAUSE IN YOUR EXPERIMENT
  The difference between your control group and
   experimental group(s).
  What you are testing.
  Plotted along the X-axis
  Ex. artificial plant


 Now you can run a great experiment!!!
 But how will you know the results???
The measured result of your experiment is the
        DEPENDENT VARIABLE

  THE EFFECT OF YOUR EXPERIMENT

  The observable result of your experiment.

  Plotted on the Y-axis.

  Dependent variables are caused by the independent
   variable.

  You take some sort of measurement and record it.

  Ex. stem height in centimeters
  TITLE: A comparison of a car’s value related to its’ mileage
            Y axis



(dollars)




                                                        X axis


                                   (miles)
When is a line graph appropriate?
When is a bar graph appropriate???
What’s the deal with this double bar graph?
Why the pie chart?

Display parts of a whole.
ANALYSIS
• ANALYSIS:
• What were the results and what do they
    mean?
•   Was data good or bad?
•   Were mistakes made?
•   Make a conclusion- does the data
    support or refute the hypothesis? What
    if neither??? Inconclusive…
•   What should be done next? Design your
    next experiment.
          DRAWING CONCLUSIONS
1.   INFERENCE- a conclusion made on the collection of facts not on direct
       observations. = hypothesis

      ie. Owl pellets let you know what it ate.

2.   MODEL- explanation supported by data.

      ie. Atom structure or structure of the universe

3.   LAW- analytical statement empirically provable using math- has a constant.
      Considered universal and invariable facts.

     ie. Gas Laws, Kepler’s Laws of Planetary Motion, Law of Conservation of Energy,
       Newton’s Law of Universal Gravity

3. THEORY- broad, comprehensive statement of what is thought to be true.

*few theories exist…they are supported by tremendous amounts of evidence… ties
      together several related hypothesis and may incorporate one or more laws.

     ie. Relativity, Natural Selection, Germ Theory
Theories can be proven wrong, so can Laws.
www.toptenz.net/top-10-most-famous-scientific-theories-that-turned-out-to-be-wrong.php
     Standards 1 a, b, c, d, e & g
a.   Select and use appropriate tools and technology (such as
     computer-linked probes-pH meter, spreadsheets, and
     graphing calculators) to perform tests, collect data, analyze
     relationships, and display data.
b.   Identify and communicate sources of unavoidable
     experimental error.
c.   Identify possible reasons for inconsistent results, such as
     sources of error or uncontrolled conditions.
d.   Formulate explanations by using logic and evidence.
e.   Distinguish between hypothesis and theory as scientific
     terms.
g.   Recognize the usefulness and limitations of models and
     theories as scientific representations of reality.
Standards 1 j, k, l, & n

j. Recognize the issues of statistical variability and the need
for controlled tests.
k. Recognize the cumulative nature of scientific evidence.
l. Analyze situations and solve problems that require
combining and applying concepts from more than one area
of science.
n. Know that when an observation does not agree with an
accepted scientific theory, the observation is sometimes
mistaken or fraudulent (e.g., the Piltdown Man fossil or
unidentified flying objects) and that the theory is sometimes
wrong (e.g., the Ptolemaic model of the movement of the
Sun, Moon, and planets).
THE FIRE LAB: answers
               PART I: #1-3

 Light emitted from candle, flame moving

 Orange flame on match

 Blue flame toward wick of candle

 Flame moves w/ air.

 Wick is black.
               PART II: #1 & 2

 Match burns shorter/ temperature is hotter

 The ignition of match is more volatile

 Candle burns longer/ temperature is not as hot.

 Flame is pale on candle and darker (more orange) on
  the match.
                      #3 & 4

 Birthday candle flame taller, brighter burning, burns
  more quickly, wax can drip down.

 Votive candle has a shorter flame as the wax can’t
  escape and pools at base of wick.

 The higher the surface area, lower burning (wax is
  contained) = slows the burning process, less wick
  exposed.

 Black around the wick is CARBON.
                         #5

 Beaker: flame to the bottom of the beaker: glass
  turns black.
                      #8

 Physical & Chemical change difference is
  that the molecules remain the same just
  change their state of matter (solid, liquid,
  gas) where as a chemical change breaks
  bonds and forms new bonds creating new
  molecules.
 Black soot is carbon = chemical change of
  the wax.
 the wax from solid to liquid to gas = physical
  change
                          #9

 Oxidation = burning sugar in our bodies to get
  energy.



 Cell respiration (in mitochondria)
                PART III: 1 a-d & 2
OBSERVATIONS
 Flame gets smaller and flame goes out

 Water rises in the beaker (higher than level outside the beaker.)

INFERENCES/HYPOTHESIS
 Heat up the gas molecules and the gases expand.

 Flame goes out when there is no oxygen left.

 When the flame goes out the molecules cool down and contract pulling
   water into the glass beaker.
LIGHT TWO CANDLES
 Will happen faster??? Two flames use up the oxygen faster.
 HOW TO VIEW A FLAME…

 More complete burn of gas (flame turns blue)
  releases the most heat.

 More incomplete burn of gas (flame turns
  orange/yellow) is good for giving off light.

 Carbon monoxide, which is toxic, is given off w/ an
  incomplete burn. SCARY.
PART IV

#2

1) Wax + O2 -> CO2 + H2O + Energy (FULL BURN)

 Blue flame = most complete burn… means more oxygen getting
     in (at bottom).

2) Wax + O2 -> CO + H2O + Energy (MIDDLE burn)

 Orange or dark part of flame in the middle

3) Wax + O2 -> C + H2O + Energy (most incomplete)

 Smoky part of flame at top
#2: What is the significance of this
        information????
 Candles used to see (light energy) orange/yellow.

 Burning for heating energy- blue… more complete
  burn.

 Burning sugar in your body…

 OXIDATION = energy formation in our bodies- sugar
  is burning to make energy. This is why you need
  oxygen to live!!!!
Steps of the Scientific Method

1.   Observation- use senses to perceive object or events.
2.   Ask Questions
3.   Collect & organize data- sample or quantitative
4.   Hypothesize- a testable explanation
5.   Experiment- testing a hypothesis under controlled
     conditions
6.   Draw conclusions
7.   Ask new questions
8.   Design new experiment
        MOUTHWASH LAB

Observations:
 People have stinky breath
 People use “mouthwash” to prevent bad breath
  and to keep their teeth healthy.
Ask Questions:
 What is making their mouths stinky? What are
  you protecting teeth from?
 Which mouthwash brand is the best one? Cost,
  ingredients, packaging, endorsements
    3. Collect and organize data

1.   Bacteria cause the bad breath and tooth
     decay.
•    Are: single-celled, prokaryotic, micro-
     organisms that reproduce by binary fission.
•    Ex. One bacterium can reproduce every 20
     minutes. Thus millions can exist from the
     reproduction of just one with in 24 hours.
•    Some are good, some cause tooth decay
     (secrete acids that are corrosive to enamel).
•    Their dying bodies and waste products they
     secrete are what make your mouth stink.
     Bacteria are alive. Need water and
   nutrients to grow. Reproduce by Binary
   Fission to form Colonies that are visible
             w/out a microscope.




                   PETRI DISH WITH NUTRIENT AGAR
                   SHOWING SEVERAL DIFFERENT
BINARY FISSION     BACTERIAL COLONIES
 MOUTHWASH INFORMATION

                     Target Scope $2.09
                     Crest Blue $4.19
                     Listerine Purple $3.44
                     Listerine Yellow $3.99

                     You might want to
                      check the ingredients
                      yourself.


Define mouthwash.
              HYPOTHESIS

 Based on the collected information, create not only
  your best guess for which one is best- but create it as
  an if then statement.



 I predict that _______ is the best mouthwash. If it is
  then ________ will happen.
        DESIGN YOUR EXPERIMENT
 Do this today.

 Conduct the experiment today. Draw exactly what your petri dish looks like today and
   mark the exact time and date.

 We’ll check the results next week.



MATERIALS AVAILABLE TO EACH GROUP OF 4:

 Petri dish with nutrient agar (it is delicate, don’t break the agar when spreading your
   bacteria on the plate.)

 1 Q-Tip (to get your bacteria sample)

 1 sharpie marker (to write on your petri dish)

 Paper soaked in various mouthwash brands & water.

 Tweezers for moving the paper discs soaked in solutions.

 Parafilm to seal the petri dish lid to the plate.
                      RESULTS

   NEXT CLASS WE WILL LOOK FOR AND MEASURE the
    absence of BACTERIAL COLONIES.

   RING OF INHIBITION- forcefield / break in the lawn.




Ring of Inhibition=
Dependent variable

				
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