The Scientific Method
Chapter 1.5
1. State the problem
The question you want to answer.
What you are trying to find.
2. Research/Observe

Anything you notice about the
problem. Anything else you can
learn.
3. Form a hypothesis
A likely, testable explanation of the
problem.
4. Test the Hypothesis/
Experiment
Experiment to find data and possible
answers to your problem.
5. Collect Data
Information (Qualitative) or
measurements (Quantitative- #s) from
the experiment.
6. Form a Conclusion
Decide what the information means.
Experimental Variables
Different factors that can change during an
experiment are known as variables.
1. Independent Variable
• Is the variable an experimenter can
change.
Is Plant Growth Affected by:
Examples:
Sunlight
Food
Change only 1 variable at a time
Water
Temperature
2. Dependent Variable

Is the variable that occurs as a result
of the experimenters’ change.
Examples:
• Size of the leaves
• Tallness (cm of growth)
Color of leaves
• Number of flower buds
Independent or Dependent?


1. You want to see if playing music
makes plants grow taller. What is the
dependent variable in this experiment?
Plant Height
Independent or Dependent?


You want to measure the effect of
different amounts of oxygen on the rate
of yeast growth. What is the dependent
variable?
Yeast Growth
Independent or Dependent?


An entomologist (bug scientist) wants to
determine if temperature changes how
many times a cricket chirps. What is the
independent variable?
Temperature
Independent or Dependent?

You think that a
certain part of your
brain is important in
memory. To test this,
you will remove this
part of the brain from
rats and see if they
remember how to get
through the maze.
What is the
independent variable
in this experiment?
When Designing an Experiment
keep these in mind!
You change only 1 variable at a time when
experimenting. The rest of the variables
you would hold CONSTANT.
1. Control Group


Contains all the parts of an experiment
EXCEPT the one experimental factor being
tested.
A control is a standard to which you
can compare your results.
2. Experimental Group

Contains all the factors of the control
group PLUS the one factor that is being
tested.
Control & Experimental Group


Harvester ants often strip a bush of all of its
leaves. Some people believe this helps the plant
grow thicker, healthier stems. In an experiment,
a student stripped off all the leaves from a set
of plants. In a second set of identical plants, the
student allowed ants to strip off the plants’
leaves. In order to improve this experimental
design, it is most important to add a set of
plants that:
HAVE LEAVES
Ants Count