Grades PreK & up. Teach and reinforce essential basic skills with these 20 self checking, five-piece simple addition and subtraction puzzles. Center piece of each puzzle features a number with four surrounding pieces that show four different ways to compute that number using addition or subtraction. Unique die cuts on each puzzle makes self correction a snap! These 8" x 8" plastic coated puzzles are durable and easy for small hands to manipulate. Includes an activity guide.