10 years old and growing; Anastasia Krupnik, by Lois Lowry. Boston: Houghton Mifflin. $6.95.

Anastasia Krupnik makes several discoveries during the year that she is 10. She discovers writing poetry, Wordsworth, memories, falling in love, and the problems that come with having a "mercurial temperament." She also discovers that her mother is going to have a baby.

The world can be difficult with such insensitive parents and a name that won't fit across the front of a T-shirt. Love isn't easy, either. When Anastasia tries to attract Washburn Cumming's attention with a frizzy hairdo, he tells her she looks like she stuck her finger in an electric socket. Washburn promptly gets moved from Anastasia's list of "Things I Love" to "Things I Hate."

Anastasia's difficulties are her own: the expected baby, an aging grandmother who can't remember Anastasia's name, and a teacher who doesn't appreciate poetry that doesn't rhyme. But Anastasia's feelings and discoveries should be familiar to anyone who has ever been 10, and author Louis Lowry has a sensitive way of taking problems seriously without ever being shallow or leaning too far over into despair.

Lowry's writing never falters. Awaiting her turn to read a painstakingly written poem in front of her class, "Anastasia had begun to feel a little funny, as if she had ginger ale inside her knees." Each short chapter of this quick-moving book reads like a small story in itself, wonderfully clear and self-contained. There is a satirical scene of a college English class, taught by the Anastasia's father, with humor that isn't lost on an adult reader or, I suspect, a younger one.

This is a brightly written, entertaining book that does a convincing job of telling what it's like to be 10, or to be alive, for that matter.