Melissa & Doug Add & Subtract Abacus is ideal for the classroom or the playroom, this classic toy gives kids lots of ways to explore numbers, colors, and patterns! Just slide the two double-sided wooden boards into the base, then encourage kids to solve equations by lining up the correct number of beads on the addition and subtraction sides or follow the patterns on the color-matching sides. This abacus is one colorful, educational powerhouse!