Sammy Harrison, age 12, of Poughkeepsie, N.Y., for his question:

WHAT IS A SONATA?

A sonata is an instrumental composition with three or four movements with contrasts both in tempo and key but related in thought. The usual four movement sonata begins with a brilliant allegro or a section that is bright, brisk and rapid in tempo.

The usual second movement is slow, rhythmic and lyrical or andante, adagio or largo.

The third movement is usually light and graceful and may be in dance form, or a scherzo. A scherzo is a passage of light or playful character.

The finale or last movement is in quick, bright tempo.

Symphonies, string quartets and long works for solo instruments use this sonata form. It has three sections called the exposition, the development and the recapitulation, which is almost a repetition of the exposition, but usually shorter.