To Nancy Pettigrew, age 9, of Denison, Tex., for her question:

 How long does it take a tadpole to become a frog?

The news frown the frog world is very sad. These charming fellows are not so plentiful., and some day frogs may be hard to find. This is all the more reason why a young person should go hunting for fog eggs and bring up a batch of little tadpoles. With proper care, most of them will live to become fogs, and you can return them to their pond.

The time to hunt for frog eggs is early spring. All you need is a glass jar. The best places to hunt are along the edges of lazy streams, creeks and quiet ponds. The frog eggs float in the water, often hidden in the water weeds. They look like masses of clear jelly spotted with black dots. Lift the eggs into your jar and fill the jar with some of the pond water. You may also add a few water weeds.

The pond water teems with tiny plants and animals too small for your eyes to see. Later, they will provide food for your baby tadpoles. Place your jar in a sunny window, for the warmth will help the little black eggs develop. In a few days, the dots look like little black commas. The round end is the head, and the tapered end is the tail of the developing tadpole.

In about one week, the babies will hatch from their jelly and wriggle around in the water. Each little fellow is about a quarter inch long. He has a flat, thin tail and a pair of tufts on the sides of his head. These tufts are his gills. He should double in size in two weeks. The tufted gills disappear, and new gills grow inside the tadpole's .skin.

If    food is scarce, the tadpoles may take many weeks to grow and develop into frogs, But if they have plenty of water weeds and pond scum, most tadpoles become fogs in about two months. Same types of frogs take longer to develop. The bullfrog tadpole does not become fully grow for a year or more

Your little darlings will grow their back legs after a few weeks. Then the front legs grow,, and their tadpole tails begin to shrink. Meantime., the gills which take oxygen from the water are changing into lungs which can take oxygen from the air. Your foster children will look like miniature frogs and come out of the water to breathe. You can now take them back to where you found the eggs and set them free.

Tadpoles in the wild lead a risky life., and most of them are devoured before they grow into fogs, Turtles and fish, snakes and birds beetles and spiders all enjoy a meal of tadpoles. But your little foster tadpoles have a much better chance because you can save them from these hungry enemies,