The document outlines the scientific method and experimental design. It describes the 5 main steps of the scientific method as: 1) making observations and asking questions, 2) forming a testable hypothesis, 3) conducting experiments to gather data, 4) analyzing the data, and 5) drawing a conclusion by accepting or rejecting the original hypothesis. It also explains key aspects of experimental design such as having an independent variable, dependent variable, and control group. The independent variable is the factor being manipulated, the dependent variable is the outcome being measured, and the control group is unchanged for comparison.

1. The Scientific
Method
&
Experimental
Design

2. • The scientific
method is a
systematic way to
help us find
answers to the
questions we
have
• There are 5 main
steps

3. • In science, we only
deal with facts
– From observations
– From experiments

4. Step 1
• Observation and
Research
–See
–Hear
–Smell
–Taste
–Feel
• For example:
I got home from school
and I smelled gas
when I walked in my
house.

5. Step 1, continued
• Observations lead to
questions
• For example: Why does
it smell like gas in my
house?

6. Step 2
• Form a hypothesis
– a statement that predicts a relationship between
cause and effect
• A good hypothesis will follow the “if…then”
format
• Example: If I smell gas, then there is a gas
leak.

7. Step 2, continued
• A hypothesis must be testable.
• For example: I can collect data (do a test) to
see if there is a gas leak.
• But if I said, If I wear perfume, then I will
smell good
• I can’t test that

8. Step 3
• Gather
data/experiment
• You can do this by
designing an
experiment, making
more observations,
taking
measurements, etc.

9. Step 4• Analyze and
interpret your data
• Look at the facts
you collected and
see if they mean
anything or give
you any answers.

10. Step 5
• Conclusion – Do you accept your hypothesis
or reject it?
• If your data supports the hypothesis, you
accept it
• If your data does not support it (even a tiny bit), you
reject it and start over

11. Let’s try it
• Step 1
Observation
The light doesn’t
come on when I
flip the switch.
That leads to a
question: Why?

12. • Step 2
Hypothesis
Use the “if…then” formula
If the light doesn’t come
on, then
The bulb is burned out
The lamp is unplugged
The power is out
Finish the hypothesis on
your whiteboard

13. • Step 3
Experiment
You can check the bulb or
the plug, try other
switches in the house,
etc. You are gathering
data to help you
answer your question.
What experiment or
data would you do
or gather?
on your whiteboard

14. • Step 4
Analyze Data
Look at the facts you gathered to see if they
support your hypothesis or not
Let’s say your hypothesis was that the power
was out and you found that none of the
switches worked. That would support your
hypothesis

15. • Step 5
• Conclusion
• Accept the hypothesis
• But if you found that the
other switches did work,
reject the hypothesis and
make a new one

16. Experimental Design
• When scientists design experiments, they must
follow certain rules.
• A good experimental design has:
– One independent variable
– A dependent variable
– A control group

17. Experiments
The independent variable is the thing you
change in the experiment

18. Experiments
The dependent
variable is the thing
you measure during
the experiment

19. Experiments
• The control group is for
comparison
• You do not experiment
on the control group

20. Let’s practice – first watch me
• Samantha wanted to know if fish breathe
faster in warm water. She set up three tanks:
– 1 with fish in cold water (10 degrees C)
– 1 with fish in room temperature water (20 degrees
C)
– 1 with fish in warm water (30 degrees C)
– Then she counted how many breathes they took
for 1 minute
So what is the INDEPENDENT
VARIABLE? (the one thing that is
different?)
The temperature of the
water
So what is the DEPENDENT
VARIABLE? (the thing that is
being measured?)
The number of breaths
Which tank is the control tank?
The one with normal
(room temperature) water

21. Let’s practice
• I want to know what kind
of fertilizer will make me
get the most strawberries
on my plants.
• Remember: Independent
Variable is what I control
• Remember: Dependent is
what I am looking for
• Remember: the control
group does not get the
independent variable
• What will be my
independent variable?
• The type of fertilizer
• What will be my dependent
variable?
• The number of strawberries
on each plant.
• What will be my control
group?
• Strawberry plants with no
fertilizer

22. Data
• Data collected is of 2 types:
–Quantitative- numbers, measurements,
etc.
• temperature, length, mass, etc.
–Qualitative – non-number data that
cannot be expressed as a number
• Shapes, colors, smells, etc.

23. Data practice...
• What kind of data
would I have collected
in my strawberry
experiment?
• Quantitative
• Why?
• Because I was counting
the number of
strawberries

24. Scientific Errors
• Poor measuring techniques
• Researcher bias
• Poor experimental design