“Solve My Riddle: A Number Line Game to Solve for Unknowns” addresses the extraordinarily difficult 1st grade skill of solving for unknowns. The CCSS for math 1.OA.A.1, 1.OA.B.4, 1.OA.D.B, and 2.OA.A.1 are addressed. This pocket game is perfect for centers, small groups, and partner play in a game format that students love to play over and over again. Additionally, it familiarizes students with using a number line, a critical skill for deep understanding of all the basic operations (+, -, x, an