It’s fun for children to plant seeds in a special container, but it can be hard to remember to water them, leading to disappointment if the plants don’t survive. Planting grass seed in some bare spots on any lawn is just as satisfying, perhaps more so because with time it will be hard to say which grass plant is the “one” they planted, and therefore they can claim the success of all. Seeds which are often successful in the classroom include:
- Mung bean seeds. These small green beans grow into the bean sprouts in Asian foods. They sprout quickly in water or in soil.
- Grass seeds.
- Mixed bird seed. Many brands contain peanuts—are there any children in your class with an allergy to peanuts?
Note of Caution! Avoid using kidney beans or fava beans. Kidney beans, when raw or slightly cooked, have a high concentration of the naturally occurring toxin, phytohaemagglutinin. In people who have inherited a deficiency of a certain blood enzyme, eating fava beans can cause favism, a type of severe anemia. Children with this deficiency may be especially affected. See the US Food and Drug Administration’s Center for Food Safety site and the Cornell University, Department of Animal Science for additional details.
Here are some ideas about where children can sprout seeds,
- Outside in a garden.
- Indoors inside a plastic bag.
- Indoors in a clear container of soil polymers (sometimes called “water crystals”), a polymer that absorbs water and has a clear, jelly-like consistency so root growth can be easily seen.
- Grass seeds are often grown as “hair” on a “head” made of a small cup of dirt with a face drawn on it. Other materials for the head include a nylon stocking foot with the seeds and dirt tied into a ball inside, and empty food containers with stickers forming the face.
After children have had some experience sprouting seeds, a simple experiment can be set up to see if varying the amount of water (which also controls the amount of air) affects sprout growth. Children may be able to design and set up the experiment, depending on their age and experience with seed sprouting and plant growth.
- Label three clear cups (see the photo below) to indicate the amount of water to be maintained in each cup. (Most three-year-olds recognize the blue color in the labels as water, and we discuss how the color is a symbol for water—the water we’re using is really clear.)
- Add the water and draw a line around the cup indicating the level to be maintained.
- Each scientist adds mung bean seeds to the cup that they feel is the best environment for successful sprouting. Some children put seeds into certain cups because their friend did, or because no one else did, not because they are thinking about what will happen. (It’s a fine line between talking about experimental design so much that the excitement disappears while waiting for action, and trying to make sure the children’s choices are motivated by some thinking about the needs of seeds.) Then additional seeds are added (by an uninterested party!) to make the number of seeds equal in each cup.
- Have the children draw the 3 cups and contents.
- Tell the children that the cups are the same, the number of seeds is the same, and the location of the cups is the same, and ask them what is different? Most of the children will be able to identify the different amounts of water but few (if any) will comment on the seeds’ access to air.
- The seeds will sprout within a week and by the second week it will be evident which cup provides the needed environment. Maintain the marked water levels by adding a little if necessary.
(Spoiler alert: stop reading here if you don’t want to know the results of this experiment before you try it yourself.)
No change will have occurred in the cup with no water, the cup with a lot of water will have sprouted and rotting beans, the cup with a little water will have bean sprouts with bright green leaves above the water and roots in the water. Discussion of personal experiences with “too much water” and drawing the results may make the children aware of how access to air is important for plant growth.
What development towards understanding concepts such as, what is alive, needs of seeds and plants, and what is air, have you seen in your class?