Students love catching mistakes, especially in the classroom. In What's Wrong with This Picture , students are told in advance that at least one of the problems on each page is correct and at least one is incorrect. They must identify which is correct and which problem is incorrect. For each incorrect problem, they must explain why it is incorrect. Watch students search for errors and in the process, learn critical thinking skills. There are 50 student activities, each with three to four geometry problems. The problems are usually visual but there are also word problems and proofs. Michael Serra, 60, paperback, Playing It Smart, 978-1559535847