Rekenrek

One, two or three rows of ten beads, five red and five white. Slide beads to show a number, see it as fives and tens, and flash a quick-look picture that is then covered.

How to use it

Choose one, two or three rows. Tap a bead to slide it, and all the beads before it, to the right. Tap the last bead moved to slide it back.
Read the total and the number sentence beside the rack. Numbers over five are shown as five and some more, and numbers over ten as ten and some more.
Press Flash a picture (or Q) to show a two-row picture for two and a half seconds and then cover it. Ask how many and how students saw it, then press Space to uncover it.

Ideas for class

Slide 7 across on the top row and ask the class to say it as five and two before you say anything. Repeat with 6, 8 and 9.
Show 8 on the top row and 5 on the bottom, then ask how to find the total quickly without counting every bead. Many students go to ten and three more.
Use quick look for pairs such as 6 and 4 and ask every student to hold up how many they saw, then discuss the different ways of seeing it.
Slide the whole top row across and ask what is left on the bottom row if the total is 14. Compare with the ten frame.
Ask students to show a given number two different ways on the two rows, such as 9 as 5 and 4 or as 6 and 3, and read both sentences.
Show 10 on the top row and ask the class to make 17, then 12, and to say what they changed each time and what stayed the same.
Use three rows to show 25 as ten, ten and five and ask how much larger it is than 20.

Questions

What is a rekenrek?

A counting frame with rows of ten beads, five red and five white, that slide along a rod. The colors let students see a number as five and some more without counting, so that quantities up to twenty become patterns they recognize.

Why does tapping a bead move the beads before it?

Because on a real rekenrek you push a group of beads across in one move, not one at a time. Tapping the fifth bead slides five, which makes the five-and-five structure easy to see.

What does quick look do?

It shows a random two-row picture with a total of up to 20 for two and a half seconds, then covers it. Students say how many they saw and how they saw it, which builds the habit of seeing groups, not counting singles.

Can students use it on their own tablets?

Yes. Each bead is a large button that works with touch, a mouse, or the keyboard, so a student can use the rack on a tablet without help.

Does the tool keep any record of what students do?

No. The beads live on the page until you close or reload it, and nothing about taps or answers is stored or sent anywhere.

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Using the rekenrek in class

A rekenrek works because it makes five and ten visible. A student who has slid seven beads across does not need to count them: five red and two white is the number. That is the structure of mental addition, and a few minutes a day of showing numbers on the rack builds it faster than drills.

Begin with the top row only and numbers to ten, saying each as five and some more.
Add the second row and ask for totals to twenty, going through ten as a stopping point.
Use quick look to show numbers for a short moment and discuss how students saw them.
Move from showing a number to showing a sum, and then to the missing part.

Common mistakes

Counting from the left one bead at a time even after a group is shown. Ask for the red and white parts instead.
Sliding only the single bead that was tapped, not the group. Say aloud how many were moved.
Reading 13 as 1 and 3 beads. Name the full top row as ten before the three more.