Have students fold a paper towel in half and crease it. Unfold the paper towel and poke several holes along the crease with a pencil; seven or eight should be enough. Place a bean seed (kidney, lima or black) over each hole, making sure that none of the seeds are touching. Fold the paper towel in half again to create a pouch, then staple the open edges closed. Dampen the paper towel -- being careful not to soak it -- and place it in a plastic storage bag. Leave the top of the storage bag open, tape it to cardstock and hang it in a warm, well-lit area. Ask the students to observe how the seeds grow over the next few weeks.
This experiment is conducted exactly as the original, but instead of several seeds of the same type, students each receive three seeds -- one bean, one corn and one radish. Have the students label each type of seed on their paper towel. During the course of germination, ask the students to record how the different types of seeds are growing. Ask the students questions to encourage their scientific reasoning. Does one type of seed grow better than the others in this environment? If you were a farmer, which type of a seed would you like to grow and why? What do you think causes some seeds to grow better than others?
This variation of the experiment tests seeds of various ages to determine if they are still capable of germination. The adult overseeing the experiment should provide the students with seeds of different ages, ranging from recently purchased to seeds from two-to-four years ago. Most vegetable seeds are good for three years, so be sure to have some seeds older than this. Ask students to label each seed with its age. Have the students record their observations. Which seeds grow the best? Are some seeds too old to grow? Can you tell which seeds are older than others, even if they grow?
This variation of the experiment is used for larger seeds, like pumpkin seeds, in order to ensure that they receive enough moisture and support. After placing the seeds on a paper towel, instead of folding the paper towel in half, place a second paper over the top of the first. Cover the seeds, then roll the two paper towels together. Moisten the paper towels and proceed with the same steps as the original experiment.