Coral reefs are built by the action of millions of tiny stay-at-home animals which live in colonies. Each animal has a small cylindrical body with a number of tentacles around a mouth at one end. The tentacles work to catch smaller animals and bring them into the mouth.

A neat answer to your question is that geologists classify rocks into three types according to the way in which they were formed. IGNEOUS rocks such as granite were formed by the cooling of hot liquid magmas from deep down in the earth. SEDIMENTARY rocks were formed by the settling and cementing together of smaller particles. Limestone is a common example. It was made from the shells of marine animals that had been ground up by wave action.

As other green plants, trees have leaves that contain little green chemical factories. These are able to use the energy of sunlight to convert carbon dioxide and water into chemical compounds such as sugars. As a by-product of that chemical reaction oxygen is given off.

There are a number of molds that will grow on bread. I think the most common is called (naturally) the bread mold, Rhizopus. With a magnifying glass you may be able to see that the bulk of the mold is a mass of tiny colorless threads that grow down into the bread. They make enzymes that dissolve and digest the bread into goodies that they can use for growth.

I believe you want to know how an airplane can fly. There are two parts of the answer to that. First we need some kind of engine to make the plane go forward through the air.

The simplest light bulb, the one that screws into a lighting fixture, is called the incandescent lamp. If you can find one with a clear glass bulb, you will be able to see the parts inside. Two rather heavy and stiff wires lead up from the base. These are made of an alloy, a mixture of iron and nickel.

You also could ask why rainbows are always in the form of a bow or arc. Actually, they are always pieces of a circle. A rainbow is made by rays of light from the sun which are bent and reflected by raindrops so that they come back to your eyes. Blue-violet light is bent more than red, so you see a band of light with all the colors in between spread out in order.

Hail usually occurs in the big black clouds of thunderstorms. These have strong winds inside, some blowing upward so that the air is expanding and cooling. The low temperatures lead to the freezing of raindrops into ice pellets. The pellets are carried in the churning winds inside the cloud.

Soap can be made from any animal or vegetable fat. When treated with an alkali, such as sodium hydroxide, the fat is broken down (hydrolyzed) to glycerin and alkali salts of the fatty acids. A common soap is made: sodium hydroxide + palm oil = sodium palmitate (soap) + glycerin. The glycerin and any excess sodium hydroxide can be washed away, leaving the soap.

I have never met a crocodile or an alligator face-to-face. So I will quote an answer to your question once written by my late friend, Dr. O. P. Breland. “A crocodile’s head narrows sharply from the level of the eyes toward the tip of the snout, and when the jaws are