Science is a hands-on based activity for 3- to 5-year-olds. Preschoolers aren't ready to sit down and memorize concepts. Encourage activities that promote a basic understanding of the world around them with activities that teach the basics in an enjoyable way. They will think they are playing when actually they are learning.
Help preschoolers create a replica of a seed's life cycle. Use eggshell halves, paper cups or small plastic pots to plant the seeds in. Help the children fill the cup with potting soil. Explain how the soil gives the seed the food it needs to grow. Help each child plant seeds in her cup. Choose seeds that grow easily and quickly such as lettuce or sunflowers. Place the cups in a sunny window and explain how the seeds need sunlight to grow strong and healthy. Water the plants as necessary. Let the children watch as the seeds grow. Point out that the leaves always reach for the sunshine and that is how the seed knows which way to grow. If planting an edible, such as lettuce harvest the leaves for a classroom snack once the plants are big enough.
Help your 3- to 5-year-olds understand the four different seasons. Make a seasonal tree to display at home or in the classroom. Create the tree trunk and branches from brown paper. Hang on a wall to display. For autumn, have the kids make paper leaves in fall colors. Take a nature walk through the neighborhood and collect fallen seeds, pods, pine cones and leaves. Tape them to the tree branches with the leaves the kids made. Explain that fall is when most trees and plants shed their leaves and seeds and get ready to sleep through winter. Cover how daytime gets shorter and it's time to start wearing sweaters and warmer clothing. In winter, remove all the leaves and seeds from the tree. Leave it bare and explain the tree is sleeping for the winter. Explain how plants, when it's cold outside, are saving their energy for spring. Explain that winter is when it is cold and that night lasts much longer than daytime. For spring, collect fallen flowers from trees and new leaves. Create flowers and leaves from construction paper. Tape them to the tree and tell the children that the plants wake up in the spring. Trees need new leaves to collect sunlight so they can be strong enough to make new seeds during the summer. The day is getting longer and the weather is warmer. In summer, place green full-size leaves on the tree. Explain that the tree is collecting plenty of strength from the sun and the dirt to make more seeds and fruit in the fall. Summer is a time for shorts and playing outside during the longer days.
Many preschoolers are enthralled with insects and bugs. Raise butterflies with the children to study the insect's life cycle. Purchase a caterpillar from an educational supply store. Keep in a tank with twigs, leaves and anything else the supplier advises for the particular type of caterpillar. Explain how all butterflies start out as caterpillars. When the caterpillar forms its chrysalis explain to the children the caterpillar is now ready to become a butterfly. When it is done it will break free of the chrysalis and be something beautiful and new. Once the butterflies emerge let the children set them free and explain the butterflies now need to find food so they can go out and make more caterpillars.