How the Rekenrek Supports Number Sense

What’s Red and White All Over? 

How the Rekenrek Supports Number Sense in Pre-K–Grade 5 

By Christine Hopkinson 

The rekenrek is a versatile math tool that is visual, tactile, and affordable. Its red-and-white bead structure makes number relationships easy to see and gives students a clear, visual way to think about quantity and place value. 

This post shares eight downloadable rekenrek mini-lessons for Pre-K through Grade 5 that teachers can use to support number sense in the classroom. Each lesson highlights a specific mathematical concept and shows how the structure of the rekenrek helps students see and reason about numbers. 

Why the Rekenrek Belongs in Every Math Classroom 

Sometimes the most powerful math tools are the simplest ones. The rekenrek, also called an arithmetic rack, is one of those quiet heroes. Unlike an abacus, the rekenrek is purpose-built for developing number sense, not just counting. An abacus uses columns of beads to represent place value, while a rekenrek is a Dutch counting and calculating frame with two or ten rows of ten beads. The rekenrek bead structure visually shows how numbers are composed and decomposed in our place value system.  

Compared to managing 100 loose counters or bundling blocks, the rekenrek is a single, easy-to-use tool that keeps students focused on mathematical relationships rather than materials. 

The 20-Bead Rekenrek: Building Early Number Sense in Pre-K–Grade 1 

The 20-bead rekenrek is arranged in two rows of ten beads, split into groups of five and five with sets of red and white beads. This design invites young learners to see and conceptualize numbers in relation to 5 and 10 rather than count them one by one. 

With a 20-bead rekenrek, students: 

• Develop subitizing by instantly recognizing quantities within 5 and 10. 

• Build fluency with numbers to 20 through seeing part-whole relationships.  

• Explore addition and subtraction strategies that are effective and efficient.  

• Strengthen relationships of numbers to benchmarks of 5 and 10. 

It is especially powerful in Pre-K through Grade 1, where children are learning that 8 is eight ones but also “five and three” or “ten minus two.” 

The 100-Bead Rekenrek: Extending Thinking to Place Value  

The 100-bead rekenrek expands the same visual logic. With ten rows of ten beads, students can model numbers using a base ten place value structure.  

With a 100-bead rekenrek, students: 

• Develop place value understanding through groups of tens and ones. 

• Practice counting by 10s and 1s with strong visual support. 

• Model addition and subtraction within 100, including regrouping. 

• Compare numbers and reason about magnitude and distance. 

• Gain conceptual understanding of decimals to the hundredths place.  

• Round whole numbers and decimals.   

Because the structure remains consistent, students can easily apply strategies they learned with the 20-bead rekenrek to more complex numbers. 

Why Teachers Love the Rekenrek 

The rekenrek supports mental math, math discourse, and visual reasoning. It encourages flexible strategies and invites students to explain how they see a number rather than just state an answer. Whether used in whole-group number talks, small-group intervention, or independent exploration, the rekenrek helps make mathematical thinking visible. 

In short, the rekenrek is not about moving beads. It is about building a lasting, visual foundation for how numbers work. Once students learn to see numbers this way, the math sticks. 
 
How does the Rekenrek Build Number Sense? 
 
Subitizing: The rows of 10 beads, 5 red and 5 white, support students to recognize "how many" beads without counting each bead. For example, they may "see" 7 as 5 red and 2 more white or 3 less than 10. 

 
Counting: Students can see (and touch) as they count forward & backward (needed to support subtraction), skip count (10s, 5s, etc.), or count on from any number. 
 
Base Ten: Students can act out how 10 ones (beads) composes 1 ten (row), and 10 rows of tens compose 100, how teen numbers are 10 (1 row) and some ones, how multiples of tens are rows of 10 beads, and how 2-digit numbers are rows of tens and some ones. 
 
Partners to 10/100: Children can easily make and see partners to 10 by manipulating the beads in a row and partners to 100 by manipulating rows of 10. 
 
Decimals: Older students can model tenths and hundredths when the 100 bead rekenrek is seen as "1 whole". 1 row is "1 tenth" and a bead is "1 hundredth". For example, 12 hundredths would be one row (tenth) and 2 beads (2 hundredths). 
 
Addition and Subtraction: Figuring out 10 more and 10 less is a cinch! Just slide a row of 10 beads. And students may use strategies such as make ten or make the next ten to develop mental math strategies. The rekenrek is a scaffold for this strategy where students can "see" the next ten AND how many more are needed to make ten.  
 
Equal Groups: Rows of beads may be used to represent arrays as models of multiplication and division. The 5 red and some white are a beautiful example of making problems easier using the distributive property. Model 4 rows of 7 on the rekenrek - do you "see" 4 x 5 in red and 4 x 2 in white? 
 
Rounding: When rounding a number such as 67 to nearest ten, the beads clearly show that 67 is 7 beads from 60 and 3 beads from 70. 

 

Looking for a Valentine’s Day math idea?  

We have written several mini-lessons to engage your students in meaningful, hands-on math. Bonus, red-and-white beads fit right into your classroom celebrations! 

View or Download Collection of Eight PDF Mini-Lessons 

 
Additional Resources:  
View our Rekenrek Collection 

Video: Working with the Rekenrek 

Working with the Rekenrek book 

Working with the 100 Bead Rekenrek book 

Virtual Rekenrek Resource