Rekenreks

What is a Rekenrek?

Rekenreks are tools also known as math racks, arithmetic racks, or calculating frames. Researchers at the Freudenthal Institute in the Netherlands developed them to teach number sense. You can buy two versions- a smaller one with two rows of ten beads or a larger version with ten rows of ten beads. While the larger version is similar to an abacus, the key difference is the color change. The color of the beads changes after 5 beads, so each row has 5 red beads and 5 white beads. This is so students can relate quantities to the benchmark numbers of 5 and 10.

You can buy rekenreks or make your own using these instructions.

Why Use a Rekenrek?

Rekenreks build students’ number sense and understanding of the relationships between numbers. They are a strong visual model that allow students to build numbers using five and ten as benchmarks. Rekenreks help students learn to subitize, or use visual patterning skills to recognize how many objects are in a set without counting. Students see numbers in groups instead of having to count each individually. They also help students develop addition and subtraction strategies for both single and double digit numbers. They are most appropriate for grades preschool-2, though older intervention students will find them helpful.

Rekenrek Activities

Have students quickly move certain numbers of beads. Teach them to move numbers less than 10 with “one push” and greater than 10 (but less than 100) with “two pushes.” (This will build their foundation for understanding place value, and for later applying their knowledge of addition and subtraction facts to larger numbers.)

Find multiple ways to represent numbers with two colors of beads.

Students can model addition and subtraction problems and strategies on the rekenrek in the same way they would with counters or unifix cubes. The rekenrek will help them move from counting one by one to using higher level strategies by easily starting with other numbers.

Learning To Think Mathematically With the Rekenrek is a fantastic free e book. It has 19 complete lessons for teaching using the rekenrek, starting with “meet the rekenrek” and progressing through using it to solve word problems. This book also offers more detail about the rationale for using a rekenrek.

I have also had students make their own rekenrek bracelet by stringing five red beads and five white beads onto a pipe cleaner.

Free Printable Resources

• Rekenrek prompt cards (free printable from K-5 Math)
• Free part part whole rekenrek worksheet on TPT

Virtual Rekenreks

• Free “Number Rack” rekenrek app for Apple devices
• Virtual rekenrek at Toy Theater
• Virtual rekenrek ten rows at Toy Theater

Video Resources

Got Rekenreks? 13 minute video made by Graham Fletcher about using rekenreks to teach the standards

YouTube 3.5 minute Rekenrek tutorial for K-2 teachers

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