Looking for a fun summer project? Check out this IKEA hack to make a $10 abacus into a classroom rekenrek with 100 beads. Having 100 beads can help you teach place value and number recognition to Kindergarteners and support multidigit operations for second graders. The DIY Rekenrek project is simple to make from any old abacus. I even enlisted the help of my toddler in this super easy DIY. To make the teacher-sized rekenrek:
Place painters tape going down the center and side of the abacus such that the last 5 beads on each row are between the tape strips.
Paint these beads white. I used a brush to paint them, but it probably would have been easier to use spray paint.
Use a chopstick to move the beads around as you paint.
As the beads dry, wipe the paint off of the metal rod. Don’t worry too much about the extra paint, though, because it does rub off pretty quickly as you use it.
You can repeat these instructions to paint the other side red, but I kept mine the default colors, which makes it easier to also visualize multiples of 20, because there are two rows for each color.
You may want to consider switching the side the white beads are on for the bottom 5 rows. Some 100-bead rekenreks come this way, so that students can more easily keep track of the rows of 10 because they know the top 5 rows start with red and the bottom 5 rows start with white. I hadn’t seen this strategy when I made mine, but I might consider it the next time around.
Having a large 100-bead rekenrek makes it easy to do whole group activities at the rug, because it’s big enough for the students to easily see what you’re doing. If you buy a few, you can also set up a center rotation. Your kids will love the opportunity to use the “teacher” rekenrek.
Resources
If your students are working on single-digit addition and subtraction, check out these games to support their strategies.
If you are teaching multi-digit operations, this game will engage your students and help them add and subtract big numbers, work with coins, and master the hundreds chart: Market Bay
Looking for ideas on how to use your new 100 Bead Rekenrek? Check out this blog post for more ideas.