The purpose of this activity is to allow students to think critically to answer a seemingly simple question. In this case, will plants grow better or worse if they’re given something besides water? The students will need to use the scientific method to determine a way to answer that question. They will also need to design a test to empirically show that other liquids can make plants grow just as well.
This experiment is AWESOME in a biology classroom. My sixth graders have always gotten a kick out of picking up each plant, tracking their changes, measuring their heights, and then comparing them to the other plants in the class. This could be very useful while talking about plants, germination, and how they grow.