Most plants grow from seeds, which come in a variety of shapes, sizes, and textures. Within this compact package, seeds contain everything a plant needs to grow and reproduce. Some seeds, such as grass, begin life with one leaf. These kinds of seeds are monocots. Other seeds, such as beans, begin life with two leaves. These kinds of seeds are dicots.
The outside covering of seeds is called the seed coat. It protects the baby plant, or embryo, inside the seed. The seed also contains endosperm, or a food supply, that the embryo uses to grow until the plant can manufacture its own food. In order for seeds to grow into plants, they need soil containing nutrients, water, sunlight, the right temperature, room to grow, and time. In this lesson, students will have the opportunity to observe this process for themselves.
What do living things need?
Discuss what living things need to live and thrive. They will begin with a discussion of what people need. They will compile a list that includes the following: food, water, a place to live, ways to stay warm when it is cold and cool when it is hot, and someone to care for them. They will then go through the same exercise for animals and plants. They will discover that all living organisms have similar needs. At this point, students will probably realize that seeds, which contain a baby plant, also have these same basic needs. Throughout the lesson, they will form a better understanding of this as they look inside a seed and then plant seeds and watch them grow.
Next, students will work in pairs to dissect lima bean seeds that have been soaked overnight. Using a hand lens, they observe the embryo and food supply. Then they complete a “What Are the Parts of a Seed?” worksheet, which asks them to label a diagram of a seed and write down what each part does. This section of the lesson will conclude with a review of what plants need to grow.
Now, the fun part!
Students should place one or two seeds in the hole and cover them with soil. Students are instructed to water the soil when it looks dry. They can tell when the growing plants need water by sticking their fingers one inch into the soil. If it feels dry, then watering is necessary.
Students will write down their observations on the observation sheet.
After the plants have started to sprout, go over the different parts that are emerging. Make sure that students can name these parts and describe their functions:
- Root: Anchors the plant and takes in water and nutrients from the soil.
- Stem: Helps support the plant.
- Leaves: Take in light, which the plant will use to make its own food.
On their observation sheets, students should draw pictures of the growing plant, labeling each part as it emerges.