The RekenrekThe rekenrek is a tool that was developed by a mathematician in Holland. Rekenrek means calculating frame, or arithmetic rack. It was designed to support the natural mathematical development of children. It encourages children to use strategies like double plus or minus, working with the structure of five, using compensation, and making tens. The rekenrek stretches children toward using these strategies in place of counting by ones.

While the rekenrek may seem like an abacus at first glance, it is not based on place value columns and it is not used in that way. It is broken into rows of ten with two groups of five on each row. The five structure offers visual support because the quantity of five can often be subitized as a whole.

The rekenrek encourages students to calculate a certain number using different combinations on the rack. The rack will likely stretch children to structure short cuts leading to efficiency.

Task

After many experiences of using the rekenrek during Math Workshop the students were shown a written number. Each student had to show on the rekenrek how they would represent that number.

Standard2.0 Number Sense

• 2.1 Recognize numerals

• 2.2 Connect numerals to the quantities they represent

• 2.5 Develop strategies for counting and keeping track of quantities

Commentary

When given the number 15, Ashley moved five red beads from the second row over first. She counted 5, then she moved over five red beads from the first row. She counted 10. Then she moved one bead at a time three on the top, then two on the bottom until she reached 15.