Gilbert is excited about the costume he is planning to wear in the Halloween parade at school, until he discovers that lots of others have the same costume.

On April Fools' Day, Gilbert is unhappy that everyone is tricking him and he is unable to get them back, but then he thinks of a great way to fool his best friend, in a story with tricks hidden in the illustrations for the reader to find.

Gilbert and his first-grade classmates are nervous about their performance on the last day of school, curious about the awards they will receive, sad to be leaving their teacher, and excited about summer vacation.