Experiment: Access to Soil

Materials (for each group of 3-4 people)

1. Two kidney bean seeds per student (you can use dried kidney beans from a grocery store, but bean seeds from a plant nursery will work better)
2. Sunny outdoor area or a sunny windowsill
3. Soil
4. Two small pots (you can also use plastic cups with holes cut in the bottom)
5. A paper towel (or a small rag)
6. Experiment Log (provided)
7. Measuring cups
8. Water

Steps

Note: See section “Expanding the Activity” for additional elements you may choose to include.

1. Fill one pot with soil.
2. One seed should be planted about one inch deep in the pot filled with soil. The other seed should be placed in a folded paper towel and placed in the empty pot.
3. Use the Experiment Log to write out a hypothesis for the experiment and to make initial, baseline observations of the seeds.
4. Place both pots in the same sunny location.
5. Check both plants every day and water them when the soil begins to dry out. Note: In this experiment, the soil is the only independent variable, so it is important to keep both seeds evenly moist.
6. Use the Experiment Log to note on what day the plants germinate.
7. Repeat measurements of both plants once a week. Record results in your Experiment Log.
8. Carry out the experiment for six to eight weeks and then discuss the results.

Discussion Questions

1. What happened to the seeds that were planted in soil? How tall were they by the end of the experiment?
2. What happened to the seeds that were planted in the pot with no soil (just a paper towel)? Did they germinate? Did they grow as tall as the seed planted in soil? Why or why not?
3. Do you think plants need soil to grow? Why or why not?

Expanding the Activity

1. Do more with data. You can chart whole-class data throughout the experiment.
2. Test more conditions. Plant additional kidney beans in additional pots, each with a different type of soil. Compare how the plants do in these different soil types.