HEARING WITHOUT EARS

AGES: 7 and up
PROJECT: Making a "soundscope"
GOAL: To demonstrate how some animals "hear" sound vibrations

MATERIALS

Balloon and rubber band
Soup or juice can with ends removed
1/4-inch square of silver Mylar, smooth aluminum foil or a tiny mirror
Glue stick or rubber cement
Flashlight with narrow beam
Radio or tape player

Snakes and several species of amphibians lack external ears, so how do they hear? Their secret is that they "feel" sound by detecting vibrations in the surface they stand on. This activity, which allows kids to see the vibrations sounds make, was shared with us by the North Carolina Museum of Life and Science in Durham, North Carolina.

To make the soundscope, cut off the neck of the balloon and stretch the balloon tightly over one end of the can, securing it with a rubber band. Glue the mirrored square slightly off center, being careful not to get glue on the shiny side. Hold the open end of the soundscope next to the speaker of your sound system, turn on some music, and have your child point the flashlight at the mirror so that the light reflects onto a wall. As the music plays, what happens to the reflected light? Does the pattern change when the music plays louder or when the pitch of the music changes from high to low?

MAIL-ORDER FROGS

AGES: 5 and up
PROJECT: Growing tadpoles into frogs
GOAL: To watch the process of metamorphosis

MATERIALS

The Frog Hatchery Kit from Insect Lore Products (kit No. 888; call 800-LIVEBUG) comes with a small tank, food, an instruction booklet and a prepaid coupon for frog embryos.

When we were kids, our local pond supplied us with as many tadpoles and newts as we could catch and raise. Today, though, frogs are in dwindling numbers throughout the country, so it is best to rely on scientific supply houses to bring this miracle into our homes. With a frog hatchery kit, your children can watch tiny frog embryos hatch into tadpoles and develop, over eight to 10 weeks, into frogs.

When your tadpoles hatch, they will resemble tiny fish. Like fish, they breathe through gills, which you and your kids can spot with the magnifying glass. Keep the water temperature of your tank just below 70 degrees and feed the tadpoles with boiled lettuce, bits of egg yolk, and tadpole food.

Over the next six to eight weeks, the tadpoles will grow fat around the middle, grow hind legs and feet, and then grow front legs. Then, for about two weeks, the tadpoles will stop eating. During this time, they will be living off the energy stored in their tails, which slowly shrink until they disappear. When the tails are gone, your froglings will be frogs and will be breathing with their lungs. Watch out--once frogs have hands and feet, they are ready to move!