The familiar triangle format reinforces fact families and number fact fluency. Double-sided, write-and-wipe boards focus on addition and subtraction on one side, multiplication and division on the reverse. They support algebraic skills such as equations, the commutative property, and problem solving. The set of 5 double-sided triangle boards with write-and-wipe surfaces each measure 10 in H. Size: 22.9 x 27.9 x 1.5 cm. Ages 6+.