A good sense of the number ten is critical for building young children’s reasoning strategies. Decomposing 10 into pairs in more than one way is a core activity in kindergarten. Here we see kindergarteners making the number ten on a rekenrek number rack, a tool with red and white beads in groups of 5s with 10 beads on each row. The rekenreks have two rows of beads, so the teacher uses the context of a double-decker bus so that children imagine the beads to represent people riding on the top and bottom levels of the bus.
First, children find many ways to make 10. Then the teacher challenges them to find the number that makes 10 when added to a given number. Knowing how any number from 1 to 9 relates to the benchmarks of 5 and 10 is foundational for building fluency in the early grades.
Want to give this lesson a try? Here are simple instructions to make your own rekenreks like you see in the video. Also visit the Math Learning Center to download their free PDF booklets for introducing and using a rekenrek number rack. Their free Number Rack app is a great digital tool for class demonstrations and online learning.