This essential Unifix aid is great for ordering, comparing, estimating and simple operations. Students fill their 'boats' to visualize and represent numbers. Includes ten pieces designed to fit Unifix cubes (not included, sold separately) stacked from 1 to 10 and teaching notes. Boats range from1-3/4' for a single cube to 8-1/2' for the ten boat. Grades K-2.