Once again, elementary-school detective Cam Jansen puts her photographic memory to excellent use in this series title that weaves an environmental theme into the chapter-book mystery. It's Green Day at Cam's school, and she and her fellow students are eager to hear how much they have collected in their recycling fund drive. With the proceeds, the school will install skylights in its entrance and lower its electricity use. Then the principal discovers that the students' money has been stolen. With her signature ability to click through an entire day of visual memories, Cam zeros in on key clues and helps lead the police to the thief. As usual, Adler includes sufficient context for readers encountering Cam for the first time, and Allen's pencil sketches nicely extend both the story's action and a sense of Cam's warm friendships. The environmental focus makes this title particularly timely, and teachers may want to review the story's well-integrated "green hints" with their own students.

On Green Day, a thief substitutes bricks for the many rolls of nickels that Cam and her schoolmates raised by recycling cans and bottles. With her trademark "Click!" the super-sleuth calls her photographic memory into action and unmasks the robber. Silly jokes and facts about "going green" round out the routine mystery. Black-and-white illustrations accompany each chapter.