1. Controlling Variables

2. Let’s learn about the 3 types of variables!
Hypothesis
The hypothesis is an educated guess about the relationship between the independent and dependent variables.
Let’s learn about the 3 types of variables!

3. The 3 types of variables!

4. Independent Variable
Independent Variable – the one thing that is changed in an experiment
What is tested
What is manipulated

5. Dependent Variable
Dependent Variable: the variable that is affected by the change in the independent variable
What is measured
What is observed
The data collected during the investigation
the factor that may change as a result of changes made in the independent variable.

6. All experiments should have a control group.
Controlled Variables
Constant: a variable that is not changed
Also called controlled variable
Allows for a “fair test”
Control group: exposed to the same conditions as the experimental group, except for the variable being tested.
Serves as the standard of comparison.
The control group may be a “no treatment" or an “experimenter selected” group.
All experiments should have a control group.

7. Identify the variables:
Hypothesis: If we add more air, the ball will bounce higher.
Independent variable:
the amount of air in the ball
Dependent variable:
How high the ball bounces
Controlled variables:
type of ball, drop the ball from the same height, drop the ball on the same surface

8. Identify the variables:
Hypothesis: If a plant gets sunlight it will grow taller.
Independent variable:
sunlight
Dependent variable:
Growth of plants
Controlled variable:
Type of plant, pot, dirt, water, location, fertilizer