Which way is up?

Why do plants grow with leaves and flowers on top instead of on the bottom? Try this experiment and see if plants know which way is up.

YOU WILL NEED:

* Three seeds (you can buy these at a garden center or at many supermarkets, or use seeds from a lemon or orange)

* Three small flowerpots or plastic foam cups

* Potting soil

* A box lined with aluminum foil (or an old 13 x 9-inch baking pan)

DIRECTIONS:

1. Partially fill the small pots or plastic foam cups with potting soil, add a seedling to each one, then fill the rest of the way with potting soil. Add a little water and then let them sit overnight in the foil-lined box.

2. The next day, change the plants' positions: Leave one sitting up right; lay the other two on their sides--be careful not to knock the soil out. Put the box where it will get plenty of direct sunlight. Add a little water every few days. The potting soil should feel damp, not soggy or dry.

3. Watch the plants for two weeks. What happened to the plants on their sides?

4. Roll one of the plants that is on its side to its opposite side. Check again after two weeks.

WHAT HAPPENED?

Plants need light, so they will often grow in the direction of the sun, even when they've been placed on their sides.