Yet another ninth-grader with a self-image problem (see, most currently, Hurwitz, above). But Janet Donovan's plight is so ordinary, and so un-angsty, that it's easy to respond to her. And her route to self-esteem leads through nursery-school teaching and bluegrass music, two preoccupations some kids can really connect with. Outwardly, Janet is just another girl in shapeless denims with a long braid she's forever putting in her mouth. But she knows she's good with little kids--and a summer job helping Mrs. Bailey, ""watching Mrs. Bailey's manner with the children,"" teaches her (and us) much more. There are problems, too: starched and beribboned little Cynthia, who goes berserk after Janet, trying to induce her to paint, causes her dress to get soiled; boisterous Clancy, Janet's special charge, who's now losing control, frightening even himself. ""Were both of them her fault?"" Other elements are more banal: an envious friend who belittles the job, and talks up boys; a boy who does take an interest, via the bluegrass group (led by Janet's father, in which she starts off playing the washtub); a becoming haircut and change of clothes. Best, though, is what Janet (and the reader) learns about human behavior--per Janet's problem-solving bargain with Cynthia, who'll paint if Janet will sing solo.