Variables · Grades 5–8
Practice identifying different types of variables through real-world science experiments.
Science Practice Lab
Read the experiment. Then answer each question about its variables.
Scenario
Students investigate how the number of hours of sunlight affects the height of bean plants. They use identical pots, the same type of soil, and equal amounts of water, while changing sunlight exposure.
What is the independent variable?
What is the dependent variable?
Name two controlled variables.
The independent variable is the one factor a scientist deliberately changes to see what happens. In a graph, it usually goes on the x-axis.
The dependent variable is what the scientist measures or observes. It "depends" on the independent variable and usually goes on the y-axis.
Controlled variables are all the conditions kept the same in every trial. Keeping them constant makes the experiment a fair test.
A few everyday investigations:
Ask students to phrase a question as "How does ___ affect ___?" The first blank is the independent variable and the second is the dependent variable.
How does the amount of light affect how fast algae grow?
How does water temperature affect how quickly salt dissolves?
How does ramp height affect how far a marble rolls?
Help students identify experimental mistakes, evaluate fair tests, and explain how to improve scientific investigations.
