Imagine you're a researcher studying how sleep affects mood. To explore the connection, you would look at two key "variables": sleep (how much someone gets) and mood (how happy or irritable they feel) ...

In science, a variable is something that can be changed, measured or controlled in an experiment. Scientists look at variables to understand how they affect things. A variable is any one of the things ...

Overview: Using segments from the PBS program: The Human Spark, students learn how to design and critique experiments with living subjects. In the Introductory Activity, students explore the steps ...