Show your child how to take an old aquarium and turn it into a terrarium -- complete with plants and insects! You'll need these materials:A small to medium size aquariumCharcoal (finely ground)Small pebblesPerliteSoil mixAssorted small plants, such as ivy, mini-african violets, small herb plants, or cactiGlass or plastic for top What to do: Wash and dry the aquarium. In thin layers, add the charcoal, pebbles, perlite, and soil. Make the soil deep enough to support a small plant, approximately 1 1/2 to 2 inches deep. Water plants well and remove from their containers. With a teaspoon, dig a small hole for the root and plant the herbs, flowers, and small plants. Do not put them too closely together. Now it's time to go out and find insects. After you collect the insects, put them in your terrarium. Cover the aquarium with a screen top. Place in light, but not direct sun. Water only with droplets since this will be a moist environment. Enjoy watching it grow.