Brian Ring, age 11, of Carmen, Okla., for his question:

WHAT IS USED TO MAKE GLASS?

To make glass, you must mix together a large amount of sand and small amounts of lime, soda and still smaller amounts of other materials to give the glass special qualities. The other materials may include alumina, white oxide of arsenic, saltpeter and lead oxide.

The mixture must be heated in a furnace until it is a syrupy mass. When the syrup cools, it is glass. Actually, it is a rather complicated procedure.

Glass can take many different forms. Flat glass is used chiefly in windows. Lots of the world's glass is used for packaging food, beverages, medicines and chemicals.

Glass can be spun finer than a spider web or molded into a telescope disk that weighs several tons. It can be made stronger than steel or more fragile than a sheet of tissue paper.

Lisa Klassen, age 11, of St. Catharines, Ontario, Canada, for her question: