1. Variables in Scientific Experiments & Writing Hypotheses

2. Independent Variable = “The Cause”
The one thing the scientist changes in the experiment.
The scientist controls this variable.
On a graph, it is on the x-axis (bottom).

3. Dependent Variable = “The Effect”
The results of the experiment.
What the scientist measures!
On a graph, it is on the y-axis (vertical side)

4. Control Variables
The variables the scientist keeps the same throughout the experiment.
Remember—The only thing that can be different in an experiment is the independent variable.

5. Examples
The independent variable causes the dependent variable to change. Example 1 in handout! Example 2 in handout!

6. Example 3
3. Example: Lemon trees receiving the most water produce the largest lemons.
I=_______________ D=________________

7. How to Write a Hypothesis
If_____then____ statement
If IV then DV because statement.
Example: Increased sleep may cause higher grades.
If __________________________________then
____________________________________because
____________________________________.