At a climactic moment of "The Invisible Children" (showing at 1:30 today on WDVM, Channel 9, and repeated at 4 p.m. Dec. 4) Gary Burghoff (the Radar O'Reilly of M*A*S*H" brings his left hand up close to the camera and you notice that the fingers are stunted, twisted out of shape -- a problem he was born with and will carry to his grave.

The hand used to bother him terribly, Burghoff tells Mark Reilly, a puppet with cerebral palsy, until one day he suddenly realized that everyone is unique, "there isn't another one like me anywhere in the world, and . . . it was okay for me to be different."

Burghoff and The Kids on the Block, the handicapped puppets who co-star in the CBS special, have taken on a large assignment for a half-hour -- to break down the substantial prejudices most Americans have about handicapped people. They do it with a mixture of humor and straight-out preaching that should have a significant impact on most viewers.

The puppets are Muppet-like in their appeal, simultaneously entertaining and informative, while Burghoff's earnest delivery of lines like "they don't want us to feel sorry for them or pretend that we don't see them' conveys the comforting feeling that one is participating in a morally uplifting activity.

The puppets definitely steal the show -- Blind Renaldo shows how he uses his cane, or explains proudly how Louis Braille invented printing for the blind when he was only 15 years old. Mark says that although he cannot walk, he can swim. And Mandy, who is deaf, teaches a class how to sing "10 Little Indians" in sign language.

There is much more to be said on the subject than can be crammed into such a short span, but "The Invisible Children" makes a good beginning.