Grades 3 & up. The ability to graph and read graphs on the rectangular coordinate plane is a basic algebra skill that can be mastered well before the formal study of this key subject. This set of games provides a systematic progression of experiences that lead to fluency and mastery. Where?s Wilson? introduces the process, followed by Where?s Wilma? And Integer Chess - with its own series of games. The playful, intensive practice is just what students need!