I learned about Rekenreks (or number racks) at a training recently. Wanting to give Rekenreks a try, I made 20 of them out of corrugated poster boards with chenille stems, pony beads, and black duct tape.
“Hey girls and boys!” I begin. “You know how Wreck It Ralph wanted to be a hero? Today, you are going to be a hero showing numbers super fast!”
I show the Rekenrek, explaining that it’s a way to show a number. The kids help me build a parallel between the 2 colors on a Rekenrek and the 2 rows on a 10-frame, and we stress how they are both tools for math (MP.5).
I introduce the word “subitize,” which means show a number quickly without counting, and I continue that Rekenreks are great tools for subitizing (MP.5).
We practice a few times, with one student choosing a number between 1 and 10, and everyone—including me—rushing to show that number on our Rekenreks. We hold our numbers up as we practice. I stress that we are showing the numbers that we are calling out (MP.4).
After we build several numbers, we move on to using a free program using the Promethean board along with our Rekenreks. One lucky kiddo shows the number with the pen on “the big screen,” while the rest of us use our Rekenreks to show the number (MP.5).
The program flashes the picture of the Rekenrek for a few seconds, and our fastest, most visual learners are challenged to build a duplicate model (MP.4). One lucky student at a time is selected to come up to the board, tap “Show Number,” and then everyone in the room must quickly have the number built. As we did earlier, we hold up our Rekenreks to show our numbers.
We do this a number of times, with different students coming up, and everyone building with our individual Rekenreks. 100% of students are engaged, even though only one student at a time is at “the big screen.”
Ideally, this lesson would be introduced when numbers 1-10 are the focus of instruction, but we are practicing later in the year (after my training, of course!). We have an extra opportunity today, though: because we have already practiced addition, we can utilize addition strategies when we build numbers on our Rekenreks! With 8, for instance, we have 5 and 3 more, or 5 + 3. We can focus on the combination of numbers to make 8 quickly, so we alternate between numbers less than 5 (that can be built all in one color) to larger numbers where we can quickly show and discuss combinations like 5 and 2 for 7.
We talk about how we all got faster showing our numbers, and how it was so much fun to build numbers on our Rekenrek and on “the big screen.” Several kids comment that they were faster than “the big screen” with their numbers, and I again mention the term “subitize.”
We talk about showing numbers without counting—and adding numbers very quickly. I explain this is called “fluency.” Both are important , I stress, and we talk about how big kids have timed tests for adding and things. A couple students raise their hands to say that they are ready for the big kid tests. I smile and nod.
The Rekenreks are collected and we have a sort of “family meeting” a heart-to-heart about math, and we talk again about how what we do in kindergarten is the foundation—the important beginning of all the math work we will learn as we get bigger.
To make a point, I ask a student to write a number 8 up on “the big screen.” We watch as the student quickly writes the number. I ask, “Remember when we were learning how to make an 8—how we said the number formation poem and had to think about how to write an 8?”
Students nod and say “Yes.”
“Do you see how quickly 8 was just written for us?”
Students again nod & say, “Yes.
“Writing 8 has become almost automatic—so fast that we don’t need to think about it. When we are that fast with showing numbers or showing addition, for instance, it makes it easier for us to do bigger, more complicated math! This work we did today will help you when you do algebra and calculus!”
To finish our lesson, I ask a question I ask all the time: “Who here can work really hard, do great in high school in classes like algebra and calculus, and graduate from college?”
All hands are raised. We see ourselves as math students, capable of great things!