Teaching kids about science using with seeds
As the fall weather causes plants to die down, use the opportunity to teach children a science lesson about seeds.
As the weather grows colder this fall, plants begin to die down. As we move to the next season, the harsh Michigan winter means many plants cannot survive until spring. In preparation for this, they create seeds so their children can grow into the next generation and many of these plants produce these seeds in the fall. In the spirit of the season, here are some science experiments you can try with kids, as well as some great information you can use to teach them about seeds.
- Gather seeds and nuts that you find in your yard, garden and woods and plant them. See what happens. Not all of the seeds will germinate, or start to grow. Why is that?
- Try watering the seeds that did not grow and see what happens. Many seeds will not start to grow until they are wet. Why might this be helpful for a plant?
- Some seeds need certain conditions before they will grow – this is called seed dormancy. Ask the children why it might be beneficial for the plant to have a particular type of seed dormancy.
- Some seeds need to go through a period of cold before they will germinate. Some seeds even need several seasons of cold and heat before they will germinate. There are many examples of this type of dormancy, in which seeds will not germinate if you put them directly in the soil. Instead, they need to be refrigerated for several months first. How might this benefit the plant? Interestingly, red oaks must have a period of cold before they germinate but white oaks do not. How might this affect where and how they grow?
- Different seeds need different amounts of light to grow: some need to be exposed to light before they will germinate, others need complete darkness. Lettuce is a good example of a light germinated plant. Peas and beans, however, germinate best in the dark. Put a mixture of both seeds on top of moist soil in two different pots. Place one in a dark room and another in a room with light. Ask the students to predict what happens, then observe.
- Certain seeds have a tough outer coating that needs to be physically scraped away before it will grow – this is known as scarification. The process of removing the outer coating can be done with sandpaper by a gardener, but how might this happen in nature? Why might plants have this type of seed dormancy?
- Some seeds need to go through an acid, like the acid in the stomach of animals, before they will germinate. What advantage might this give a plant? Do you think there is anything you could do to simulate this, so you could gather seed without picking through bird poop?
- Certain seeds need to be exposed to fire or intense heat before they will germinate. The Jack Pine is a good example of this. What advantage would there be to a tree if it started to grow right after a forest fire? What effect does stopping forest fires have on the environment?
- Other seeds, including tomato and cucumber seeds, need to be slightly fermented before they will grow. Allow a cucumber and tomato to ripen fully and then gather the seeds, along with the gel-like liquid surrounding them. Place the seeds and gel-like liquid in a lidded jar with some water. Shake the jar a few times a day. The mixture will ferment and the viable seeds should sink to the bottom within five days. Pour off the liquid and any floating seeds, and then set the remaining seeds to dry on coffee filters.
- Some seeds need to be fully mature before they can be planted. For example, bell pepper seeds are not fully mature until the pepper has changed from green to another color. Therefore, even though there are seeds inside a green pepper, they will not grow.
Michigan State University Extension recognizes there are many opportunities for science education that occur in the natural world, including this one with seeds. This lesson can be conducted by any group working with children, including families, day cares, schools or 4-H clubs. Have fun experimenting with seeds and stay tuned for the next article, which discusses seed dispersal.