Secret Sister by Martha Tolles

This novel would probably appeal to girls around the age of twelve. The characters, dialogues and actions are realistic. Secret Sister is a program at this school a bit like our Book Buddies to encourage friendships. Can you imagine leaving notes to a secret sister at school? Darci is assigned to send notes to Crystal, a popular student and tv star. But will Crystal want to be friends with Darci once sh finds out who she is? And, who is sending Darci notes? It seems to be someone very strange. Can you work it out?