Yusef is doing an experiment to find out how the amount of sunlight affects the growth of a seedling. He has three identical pots containing grass seeds he planted at the same time. He puts them in windows that receive different amounts of sunlight each day. Every day, Yusef looks at the pots and records his observations. What is the independent variable in Yusef's experiment?

The independent variable is the amount of sunlight, and the dependent variable is the growth of a seedling. An independent variable is something you have control over or can manipulate to affect the dependent variable. In this case you want to know the amount of sunlight that affects the growth of a seedling. You can manipulate sunlight by putting the pots in windows that receive varying amount of sunlight. There are cases when independent variable is fixed or cannot be manipulated. Just remember that independent variable cannot be changed by other variables you're measuring.