Going on Twelve by Candice F Ransom (paperback) Apple Publishing, Scholastics. 1988
Sixth grade is off to a bad start for Kobie. First she is replaced as class artist by John, the nerdy new kid, and the class blames Kobie when the mural loses the school competition. Then, when she and her best friend play a joke on John, it backfires and lands them in all kinds of trouble!
