Monday, September 10, 2012

What is a Rekenrek?

Directly translated, rekenrek means calculating frame, or arithmetic rack. Adrian Treffers, a mathematics curriculum researcher at the Freudenthal Institute in Holland, designed it to support the natural mathematical development of children and to help them generate a variety of addition and subtraction strategies. 

Students can use the rekenrek to develop computation skills or solve contextual problems. Once children understand the operations of addition and subtraction, and can model various situations, it is important that they automatize the basic facts by finding and using patterns and relationships. 

Unlike drill and practice worksheets and flashcards, the rekenrek supports even the youngest learners with the visual models they need to discover number relationships and develop automaticity.

The rekenrek looks like an abacus, but it is not based on place value columns or used like an abacus. Instead, it features two rows of 10 beads, each broken into two sets of five, much like the ten frames.

How to Make a Class Rekenrek

First get a sturdy board. I used a large foam board (20"by 30") that I purchased from Hobby Lobby for $1.99. The clerk was nice enough to cut it in half for me so I can make two!

Next, I drilled two holes on each of the short ends. The holes are 4 inches in and 2 inches from the ends.
Gather scissors, 20 unifix cubes (10 blue and 10 red and free from your math manipulatives), and string. I used S'getti Strings that came on spool of 50 yards for just $1.99.

Then string them up! 

And tie them in the back! 

Now you have a classroom rekenrek (priceless!)

You can also download a free app called Number Rack. 

Your students each need one too! Use poster board, mat board or any stiff cardboard you can get your hands on. I cut my boards into 8 inches by 4 inches pieces but you can do whatever size works for you. Use red and white beads and the S'getti string just like your classroom board. Now you are ready to go!

Here is a confession from a 2nd grade teacher:

Give it a try and let me know how it works. 


  1. What is s'getti string and where can I get some?

    1. You can find it at Hobby Lobby, here is a link:

      Any string could work though!