According to the National Standards for Science Education in the United States, students must know about "the characteristics of organisms, the life-cycles of organisms and organisms in their environments" by the time they graduate from fourth grade. Projects utilizing plants are not only an excellent way to achieve the national standards for third graders while providing their ever-so-curious minds with hands-on experience, but also a wonderful opportunity to work together in a natural environment.
Characteristics of Plants
Projects that illustrate the characteristics of plants entail: detailing the parts of plants; discussing the nourishment plants need to grow; and focusing on the unique characteristics of each plant species. Simply growing the same seeds in different controlled environments and labeling the parts of the plants in a diagram as they appear is an excellent way to identify the parts and nourishment needs of a specific plant variety.
As the plants grow, measurements can be taken and applied to a graph or chart to initiate a discussion about plant nourishment. The healthiest plants can then be transplanted outside to continue and conclude the project. In order to demonstrate the differences between plant species, the entire process can be repeated using different species of seed. The diagrams between plants can be compared and contrasted to illustrate the different characteristics between plant species.
Seeds chosen for this project should be familiar to the kids, and fast-growing: sunflowers, beans, marigolds, carrots, and many other annual and vegetable plants are typically the best known and easiest to grow. Likewise, keeping the experience hands-on by enabling the children to care for the plants themselves is another way to maintain interest for the duration of the project.
Life Cycles of Plants
By starting plants from seeds and propagating existing plants, children can understand the life cycle of a plant. When lima beans are soaked overnight, their outer shells become soft. The soft outer shells can then be pried apart to reveal the baby plant and its food source (cotyledon) inside.
Exposing kids to this simple fact begins their understanding of the plant life cycle. A full lima bean can than be placed on top of a wet paper towel in a zipped-up plastic bag to enable kids to see how a seed germinates and grows. Popcorn seeds are another fun and familiar seed to plant in this manner. Cutting the top off a carrot or pineapple and placing the top half in water is an intriguing project to illustrate propagation of a plant. Children will love watching the carrot or pineapple regenerate itself within a matter of days.
Plants in their Environments
Using different types of planting mediums and temperatures is a great way show how the environment effects the growth of plants. Allowing kids to observe the same species of plant in different soils, different mulches, and different air temperatures will drive this point home. A very fun project for children of all ages is to make a worm farm out of a plastic storage tub. The castings or waste from redworms can be used as a natural fertilizer to grow plants. The plants grown with the castings can than be compared and contrasted to plants that were grown without the castings.
The worm project may take a bit of time, but inevitably the kids will learn about the importance of worms in the environment, how to recycle food products, and how to raise "pet" worms at the same time.