Aaron Wilson, age 13, of Champaign, I11., for his question:

HOW IS PLYWOOD MADE?

Plywood is a building material that is made by a number of thin ,layers of wood glued together. The layers are arranged so that the grain direction of one layer is at right angles to the next layer, giving the piece of plywood great strength.

Plywood is made by using logs that are free from knots and decay. After being steam heated, the logs are put into a lathe or slicer to be turned into veneer. About nine tenths of all veneer is rotary cut with a lathe.

The log is placed in a lathe and then revolved against a stationary knife extending across its length.

After the thin slices, or "plies," are dried, trimmed and matched, a layer of glue is applied to each ply. Giant hydraulic presses squeeze the plies together with heat and pressure. Then the finished plywood is again dried, trimmed, sanded or otherwise finished into sheets.