Green plants need sunlight to live and grow. They use the light's energy to grow. All animals get their food from plants, either directly or indirectly. Since plants need sunlight to grow, all living things depend on the sun.

GROWING WATERCRESS

1. Put a layer of cotton in the bottom of two clean dishes. Add a little water. Sprinkle watercress seeds evenly over the cotton.
2. Put the dishes on a sunny windowsill and cover each dish with a cardboard box and leave for several days. Check daily that the cotton is damp.
3. The seeds under the box with no hole have grown straight up looking for the light. The watercress under the box with the hole has grown toward the light.

WHY IT WORKS
Green plants contain a chemical called chlorophyll. Chlorophyll traps light, which combines with water and air to help make plants grow. This process is called "photosynthesis." Plants cannot see light but can bend and grow toward where it comes from.

FURTHER IDEAS

Follow step 1 again. Cover one dish with a large, clean glass jar to make a "greenhouse." Compare the growing roots and shoots with the uncovered dish. Which seedlings grow the best?

Colored Dyes

Today we can buy clothes in an enourmous variety of colors. These colors come from modern artificial dyes made from oil. Before the nineteenth century, people had always used natural dyes made from plants, animals, or materials in the ground.

TIE-DYE A HANKERCHIEF

1. Collect lots of brown onion skins. Ask an adult to boil them in water for 20 minutes.
2. Tie some string around a white cotton handkerchief as tightly as you can.
3. Soak the tied handkerchief in the onion skin water for five minutes. Use an oven glove to protect yourself.
4. Cut the string from the dyed handkerchief when cool. Fasten the handkerchief to a clothesline until it is dry.

WHY IT WORKS

Onion skins contain a chemical called a pigment. Boiling brings out the pigment, which in onion skin is yellow. Compare how well the pigment dyes fabrics other than cotton.

FUTHER IDEAS

Many vegetables contain different colored pigments. See what color beet juice or spinach water dye fabric.