Earthworms produce excellent fertilizer through the waste they expel. For a long-term project, compare fertilizer produced by earthworms to commercial fertilizer. Place eight to 10 redworms in a clay pot. Add potting soil, sand, grass clippings and shredded newspaper. Plant five fruit or plant seeds in the pot. Repeat this process with a second clay pot using fertilizer instead of earthworms. Put the pots in a high-sided open cardboard box and place in a well-lit, warm area. Water the plants as needed, and record your observations of plant growth over the next six weeks.
Examine an earthworm's sensitivity to colored lights. Line a cardboard box with moist topsoil and grass cuttings, and add one or more earthworms. Ensure the box has a lid. Open the lid and shine a flashlight covered with red cellophane directly at the earthworm. The earthworm will likely not react. Shine the flashlight through a piece of blue cellophane. The earthworm should move away. Experiment with different colored cellophane and record your observations.
Learn about an earthworm's sensitivity to touch by developing a science project based on reaction to touch. You will need a feather, a paint brush, an ice cube and a leaf. Remove the earthworm from the cardboard box and place it on a damp piece of paper towel. Gently stroke it with each item. Record the reactions. During a science fair presentation, ask spectators to try this experiment.
Earthworms make excellent composters. Use five 10-inch clay pots to compare the effect of having more earthworms in an area. Fill each pot with moist soil, leaving 2 inches at the top. Leave the first pot empty, and add 10 worms to the second pot, 20 to the third, 50 to the fourth and 100 to the fifth. Once the worms have burrowed down into the soil, fill each pot with grass cuttings. For the next four weeks, measure the level of the cuttings with a wooden ruler. Record your findings.