This new picture book by Erica Perl celebrates the imaginary friend. Ida's special friend, Dotty, comes to preschool with her at the end of a blue string, and there are plenty of other invisible friends there to keep her company. But as the year passes and the students get caught up in other interests, there are fewer and fewer imaginary friends and Ida begins to doubt if Dotty is welcome at school anymore, until she notices that her teacher carries a red string wherever she goes...