This is a two-part activity. We recommend that you allow at least three days (up to one week) in between Part One and Part Two of the experiment to give the radish seeds time to germinate.

You will need access to a sunny windowsill for radish seeds to grow in the light. You will also need access to water so that you can fill up the spray bottles.

We suggest students work in pairs. Homeschool students can work on their own but will need to prepare at least two Dixie cups so that they can compare what happens to the plants in sunlight versus in the dark.

Prep Radish Seeds

For each group of four students, put about ⅛ teaspoon radish seeds (at least 20 seeds) in a Dixie cup.

Prep Dixie Cups

For each student, fill one Dixie cup halfway with moist potting soil. Or if you are using peat pellets, place one pellet in each cup, fill the cup with water, and let the pellet soak up the water for at least 30 minutes.

Prep Spray Bottles

In each spray bottle, mix about 1 cup of water with about ¼ teaspoon of baking soda. Adding baking soda will inhibit mold growth in the soil, but won’t affect the plants.

Plan Your Time

After students complete Part One of this activity, they will need to wait at least three days (up to one week) to give the radish seeds time to germinate. Make sure to spray both the cups in the sunlight and the cups in the dark with water during this time.

When most of the leaves have come up, show Part Two of the activity.