Monday, May 11, 2015

Building Mathematical Flexibility with the Math Rack

Hi, this is Brandi, from The Research Based Classroom. Do you teach kindergarten or first grade? Are you constantly trying to build mathematical flexibility? Whether you call it a Rekenrek or a Math Rack, you have to try this tool.

A rekenrek (wreck in wreck) is a Dutch math tool that uses two sets of ten beads. Each set of ten is made from five red and five white beads. Just the format alone helps students to start thinking about groups of five and ten. The large rack shown above comes with a removable cover so you can "hide" beads behind it.

I started with this tool by just letting the students explore and talk about the characteristics of the tool itself. Then using only one bar of the math rack I ask students to tell me how many beads they see. Learning to subitize the five and ten is a huge skill for five and six year olds and it takes some time before I start telling addition and subtraction stories. Putting the math into context through story problems helps young mathematicians make sense of the operation you are asking them to do. Later in the year as my students become proficient within ten, I move toward using both rows of beads to work with numbers up to 20.

What I found to be really great with this tool is the number of addition and subtraction strategies that my students discovered themselves and then taught to each other. The math talk is so important for this. They were counting up, counting on, doubling, halving, making ten, using doubles plus one and so on. Every strategy I used to teach was discovered by the students themselves and then taught to each other. As they became more flexible with their numbers, the discussions became more precise and I gradually increased the difficulty. At the beginning of the year I used this tool every single day for 5 to 10 minutes. Now that we are at the end of the year I'm still using it every single week.  Give it a try and you'll love it. My only disappointment is that I didn't find this tool years ago.

My young mathematicians also use student size math racks for working with partners or individually.

And they use the free app version.

My full size Math Rack at Math Learning Center is available here. They also have a free guide to using the Rekenrek here. And you can get the free app for the iPad or the web app for browsers here. The small student size rack is available here.  And a great definition of subitizing  can be found here.


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