Sally is going to change the amount of water given to the plants. This is the independent variable. Sally expects the plant height to depend on the amount of water. So plant height is the other variable that changes in the experiment. Plant height is the dependent variable.
Plants grow higher if they are given more water.
Plant four seeds in each pot. Plant each seed the same distance under the soil. Place all pots in an area so they can get approximately the same amount of light. Give the pots the following amount of water each day for 30 days. After 30 days, find the average height of the plants in each pot.