This is a hands-on introductory activity, which can be used to teach students about variables and how a controlled experiment is set up. It is designed to make the concepts concrete and easy to understand for first-time or struggling learners. Students can work in pairs or small groups, and then discuss in order to fill in the blanks on the worksheet. Teachers may also choose to set this up as a demonstration in front of the class. They can discuss the different parts of the experiment as they p