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# Rekenrek

Rekenrek! Isn’t that a fun word? It’s Dutch for “calculation rack.” Once your students have tried the fun online rekenrek, they will beg to use it over and over again!

The rekenrek was invented by mathematics curriculum researcher Adrian Treffers at the Freudenthal Institute in Holland. Our virtual rekenrek is similar to the original rekenrek designed by Treffers. It features two rows of ten beads. Each row has five red beads and five white beads, helping students visualize quantities using 5 and 10 as anchors. The rekenrek helps students build number sense, count, and perform operations.

Students can manipulate the virtual rekenrek by sliding beads to the right or left. Simply click and drag the beads! You can drag one at a time or move several all at once.

How can you use the rekenrek? Think of the virtual rekenrek as a tool similar to a five or ten frame. Here are some possible activities:

• Ask students to express a number. Boost numeral recognition by showing students a flashcard and then having them show it on the rekenrek.
• Show a number on the rekenrek for only a few seconds. Ask students what number they saw.
• Ask students to solve an addition or subtraction problem using the rekenrek to model the problem. Include problems with a missing addend or subtrahend.
• How many ways to form X? Ask students to form a given sum as many ways as possible.

Visit classplayground.com for resources and printables related to Rekenreks.

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