To the right are the main steps
of the Scientific Inquiry process
which is applied every time you
do a lab.
By the time you reach Grade 12,
you will be expected to design a
complete lab. using the Scientific
By the end of Grade 9, you should be able to successfully do the
From a stated problem, be able to make a valid hypothesis that
follows the prescribed format of “ if ...... then ...... because .....”
From a stated problem, after a valid hypothesis has been stated,
design a lab. to test this hypothesis. In order to do this, you must
be aware of :
a. the variables that can affect the data you might collect.
b. how valid your data would be if these variables were allowed to be
a part of the lab.
c. which variables are acceptable in a lab. and which are not.
d. how to control the unacceptable variables ( make sure they don’t
become part of the lab. )
e. the need to have a set up that allows you to compare the results
you get when you change a variable. This is called the CONTROL.
f. how long data should be collected for in order to produce a valid
When you do a hypothesis, you must make sure
that it fits the principle of being “an educated
This is why there is a “because” section in the
hypothesis. It makes sure that there is thought
behind the process.
You are predicting what patterns you expect to see
after you have collected sufficient data.
You are required to state what you would expect
to find if you set up a certain condition. The
condition is the “if” part and the expected
outcome is the “then” part.
Consider the following problem :
Does a plant grow faster in sunlight than in the
A typical hypothesis would be :
If a plant is placed in sunlight, then it will
grow faster than if it is placed in the shade,
because a plant uses sunlight to carry out
Write hypotheses, using the “ if ...... then
...... because ” format for the following :
1. What is the relationship between temperature
and the volume of water ?
2. What is the relationship between types of
atmospheric gases and global warming ?
3. How does the time a battery takes to die in a
laptop vary with the type of laptop ?
4. How does the colour of flowers affect the
number of visits by honeybees ?
1. What is the relationship between temperature and the volume of water ?
If the temperature is doubled, then the water will double in volume because
the molecules move twice as far apart.
2. What is the relationship between types of atmospheric gases and global
If the atmosphere contains more methane gas, then there will be more global
warming because it reflects back more heat radiation from the ground.
3. How does the time a battery takes to die in a laptop vary with the type of
If the laptop has a bigger screen, then the battery will last a shorter time,
because the extra light draws more power.
4. How does the colour of flowers affect the number of visits by honeybees ?
If the flower is yellow, then more bees will visit it because the colour yellow
is brighter than other colours.
Variables are factors that affect the results. If water
evaporates from the soil when the sun shines, a
breeze will make the water evaporate more
quickly. The breeze is a factor or variable that
changes how quickly the water evaporates. If you
are trying to see whether more sunshine makes
water evaporate more quickly, you don’t want
something else to be changing what you would
otherwise find out. The breeze is a variable that
has to be kept the same everytime we test or take
measurements. It has to be controlled.
In any experiment, you are going to see what
happens when a factor is changed. The factor
you are changing is called the independent
When you change a factor, something else will
change as a result. If this change is what you
are measuring, it is called the dependent
Only these two variables should exist for the
experimental data to be meaningful and valid.
All other variables should be kept constant ( by
not changing, they are no longer variables and
don’t exist any more ).
Inthe example above, you
would need to allow the soil
to be exposed to the sunlight
but make sure that any wind
or breeze doesn’t blow over
the soil ( or make sure that the
breeze is the same amount all
the time ).
If you want to know how much the sunshine affects the
water evaporation from soil, you want to have
something to compare it with.
This is usually done by having one additional set up
where the independent variable is not there (two set
ups - a with and a without ).
One soil sample will be exposed to sunshine and a
second sample is not exposed to sunshine.
The second sample is the CONTROL. It becomes the
comparison that allows us to see how much the soil
changes when exposed to sunshine.
You would now change how much of the day the soil
receives sunlight. This is the variable you are changing.
You set these conditions. This is the independent
You will measure how dry the soil gets ( how much
water is lost ). This is the dependent variable.
For each of the following problems that would involve carrying out an experiment
A. What would the independent variable be ?
( What would you set up as your change ? )
B. What would the dependent variable be ?
( What change would you measure ? )
C. What would be your control ?
( What would you set up as the normal to compare with ?)
1. Does light travel the same way through different substances ?
2. Does adding compost to soil promote vegetable growth ?
3. How effective are various kinds of mosquito repellent ?
Does light travel the same way through different substances ?
Independent variable - choosing different substances such as plastic, glass, water etc.
Dependent variable - measuring how much light goes through
Control - comparing the substances to air ( equivalent to no substance )
Does adding compost to soil promote vegetable growth ?
Independent variable - choosing different amounts of compost
Dependent variable - measuring how fast one vegetable grows ( measure its size )
Control - measuring one vegetable’s growth ( same kind ) without compost
How effective are various kinds of mosquito repellent ?
Independent variable - choosing different brands of mosquito repellent (different chemicals)
Dependent variable - measuring how many or how few mosquitoes come
Control - measuring how many or how few mosquitoes come with no repellent