To determine the effects of light on seeds, germinating control needs to be maintained for all other variables. The same seeds need to be started in the same medium and watered with equal amounts of the same liquid at the same time. Once this is accomplished, set four moist paper towels with five bean seeds folded into the middle of each towel on separate plates. Place one plate in a dark room, one plate in a sunny window, the third plate under artificial light that is turned off at night and a fourth plate under artificial light that is left on at all times. Have students track and record all activity with the seeds and the daily changes for two weeks. Create a graph for each plant.
To study the effects of liquids on germination, plant bean seeds in clear, plastic cups of potting soil. Press the seed against the side of the cup so it is visible during the weeks of the experiment. Have each student choose a different kind of liquid, such as water, soda, lemon juice, vinegar and milk. Add 1 teaspoon of each liquid to a 1-liter bottle of water. Label each bottle. Give each child his own cup and seed. Twice a week, have each child water the seeds with 1/4 cup of the different liquids they have chosen. Keep the plants in a sunny window. Have each child measure and record any activity with their seed and compare notes.
Plant seeds in various soil mediums. All other activity with the seeds need to be controlled. Use the same seeds and water them at the same time with the same amount of water. Plant seeds in a clear, plastic cup of sand, potting soil, dirt, vermiculite, crushed stone, clay dirt, compost, etc. Measure and record all activity with the seeds. Slide the seed against the clear plastic cup to watch the germination taking place.
Discuss with students what kinds of pollution happen to our earth. Create the effects of various pollutants causing acid rain. Add 1/2 teaspoon of baking soda to 1 liter of distilled water. Test the water with a water testing strip -- found where swimming pool supplies are sold. Check the acidic level in the water. In another 1-liter bottle of distilled water, add 1/2 teaspoon of vinegar. Leave the third 1-liter bottle plain. Water seeds that have been planted in clear, plastic cups with the same soil twice a week for 14 days. Measure and record all activity.