Cuisenaire® Rods help students transition from concrete to abstract representation of math concepts. Each colour represents a different Rod length that can be assigned a different numeric value or unit of measure. Classroom Set includes 444 Rods (in trays) for use with 12-18 students. Small Group Set includes 155 Rods (in bucket) for use with 4-6 students. Rods measure 1cm - 10cm L (0.4" - 4"). Ages 4+.