The natural world, such as the function of plants and the way they grow, is a source of wonder for many children and will be something they continue to study throughout their education. Have kids conduct plant-based science experiments during a classroom unit on nature or as a follow-up to a visit to a local park or garden.

In this simple science project for young children, fill a cup with water and add several drops of food coloring, such as red or blue. Cut the end off of a white carnation and place the flower in the cup of colored water. Have the kids watch as the flower absorbs the colored water and slowly changes color. Explain to them not only do flowers absorb water from the air, they also "drink" water through their stems.

Older children will enjoy conducting a more complicated experiment on plant growth. Have the children plant seeds in the center of two different pots filled with potting soil. One pot should be watered and set in a sunny area, while the other should not be watered and placed in a dark area, such as a cupboard. The children can then check on the plants daily and examine which pot thrives. The watered pot placed in the sunny, warm area is much more likely to grow.

Begin this experiment by soaking three beans in two inches of water overnight. The next day, remove the beans from the water and fill three test tubes halfway with potting soil. Insert the beans in the test tubes and fill the remaining space in each with more potting soil. Place the test tubes in a warm, sunny area and water them daily. The children will be able to watch the entire growth process of the beans through the test tubes. For a more complicated experiment, place each test tube in varying light and temperature conditions.

This simple experiment, which can be done indoors or outdoors, allows children to observe how plants lose water through their leaves. Place a clear plastic bag over a branch of a bush or section of leaves of a potted plant. Secure the open end of the bag with thick tape or string, sealing the section of the plant inside. Leave the experiment for 24 hours, and when you return, the kids will find that water from the plant has been drawn out and gathered in the plastic bag.