Saturday, February 13, 2016

Who wants to talk about Rekenreks?!

If you’re like us, you’re obviously jumping up and down right now yelling “I do! I do!” This is a completely reasonable response because, if you teach math, they’re just plain awesome (hence why I’m blogging about them on a Saturday night). Rekenreks, also known as arithmetic racks, act as a visual scaffold to support number sense within 5, 10, and 20. There are two rows of beads - 10 on top and 10 on bottom. Each group of ten is comprised of 5 red beads and 5 white beads, and looks like this:
We have found the rekenrek to be an invaluable tool for supporting flexible addition and subtraction strategies by visually showing students the structure of numbers to 20 in reference to fives and tens. As always, the more hands-on we can make math for our kids, the more it will mean for them conceptually! With my first graders I usually start with some basic addition skills; for example, if I slid over 7 beads from the top row and quickly “flashed” them to my students, they could quickly recognize the 7 as 5+2 (5 red and 2 white). If I slid over 6 on the top and 7 on the bottom, and again flashed it to my students,  they would quickly see the 10 red beads and 3 white beads to make 13. Another student might look at the same set of 6 and 7 and see the doubles of 6+6, with one extra on the bottom to also make 13. This may be the simplest use of the tool but there are many, many more! I found a great, free (46 page) resource online full of instructional ideas from The Math Learning Center - check it out here!

When I am working with a small group of students, the most popular activity is something I like to call Number Detective. For this activity I start by building a number on my rekenrek by pushing the beads to the left without showing the group. I then tell my students the number I have built (pictured below, I built 6!).


The students then built the same number on their rekenrek (pictured below, the student to my right built 5+1).


They take turns showing me their rekenrek and asking, “did you build six with five and one?” etc. In this case, I said “no, try again!” Sidenote - I’m usually extremely competitive but have learned to take it easy when working with first graders. The students kept building six in a variety of ways (4+2, 3+3) until someone’s rekenrek matched mine! It’s a fun game and the kids love being the person to build the number, then having their classmates be the detectives - but more importantly, it promotes flexible addition strategies and number partitions! After all, that’s what every kid dreams about at night, right?

Your rekenrek loving interventionist,

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