Growing a flower bulb on a plastic drink bottle is no-fuss way to bring a bright spot of springtime color into your house in the middle of a dark, cold winter. It's easy enough for children to do with very little help, and they'll be able to watch through the clear plastic as the bulb develops roots, and a shoot grows from the bulb's top. After a period of darkness, bring the bulb into the light and watch the bloom burst forth. Any spring bulb, such as daffodil, tulip or hyacinth, will work.
Remove the cap from a plastic water bottle, and remove any labels. Cut the bottle in half with a sharp craft knife or a pair of scissors.
Turn the top half of the bottle so that the spout faces down and nestle it into the bottom half of the bottle. Put a small amount of water in the bottle.
Put the bulb in the upside-down spout of the bottle, with the top, or pointed side of the bulb facing up. The water shouldn't be high enough to touch the bottom of the bulb.
Put the bottle in a cool, dark place and leave it for about a month, or until the shoot is about 2 inches long. Keep an eye on the water level, and if it drops, move the bulb aside very carefully so the roots aren't disturbed, and add water to bring the level back up.
Bring the bottle out of the dark and put it in a shady place in your house for two days, and then move it into bright but indirect light for two more days. Finally, move it into a bright window and leave it until the bulb blooms.