In a time when school music classes (if they exist at all) teach their students the finer points of the themes from The Twilight Zone and Jaws instead of real music; when classical radio stations are converted to Lite Rock or switched to a "top 100" classical jukebox format; and when even churches increasingly favor banal "Jesus Is My Boyfriend"-style slop instead of Bach, Mozart, and Vaughn Williams, classical music may legitimately be seen as an endangered cultural species. Enter Scott Speck and David Pogue, who take out the unnecessary mystery, and offer an easy-to-swallow quickie education, ranging from Gregorian chants to contemporary composers such as John Adams and John Corigliano. If you can't tell an oboe from a bassoon, there's also a dandy guide to the instruments of the orchestra, and once you're through that information you'll know the difference between a concerto and a sonata. Best of all is the introduction to music theory, which actually makes a daunting subject seem easy. It's all supported by a helpful enhanced compact disc (it works in your CD-ROM drive; it plays on your stereo's CD player) containing more than an hour of representative musical tidbits from good EMI recordings. Although the tone is unremittingly flippant and the jokes are, for the most part, pretty bad, Classical Music for Dummies is one of the better works in this series, and really does provide a useful reference for a subject too often seen as arcane.