What is the Rekenrek? This Dutch word means arithmetic rack. It helps children support the natural development of number sense. Based on the concept that it is better to use 5 and 10 as anchors for counting, addition and subtraction, the Rekenrek is a tool that allows learners to create models and visualize number relationships while developing a variety of strategies for facts up to 20 or 100. This includes doubles plus or minus, unitization (decomposition of numbers), hierarchal inclusion, subtraction, making tens, compensation, increasing number and operations in base 10, and much more! Perfect for grades K-4.