# Number Rack

Available versions
Description

Slide beads to show and work with numbers and think in groups of 5s and 10s.

## App Tutorial

Number racks (also known as rekenreks) facilitate the natural development of children’s number sense. In the Number Rack app, rows of movable, colored beads encourage learners to think in groups of 5s and 10s, helping them to explore and discover a variety of addition and subtraction strategies. Display up to 10 rows, each with 10 beads, to work with numbers up to 100.

This virtual version of the manipulative is an open-ended educational tool, ideal for elementary classrooms and other learning environments that use laptops, iPads, or Chromebooks.

The number rack is a key component of Bridges in Mathematics, second edition. Online preview available.

## App Features

• Slide beads one-by-one or in groups across a row.
• Display 1 to 10 rows of beads, 10 beads per row.
• Reverse the colors of rows 6 to 10 to distinguish (or not) groupings of 25 beads.
• Hide and reveal beads with resizable covers to pose problems and play games.
• Share your work by saving an image or creating an 8-character code and link to send to others.

## Get More From This App

### Book for Educators

This book offers teachers the theoretical basis and practical knowledge to employ the number rack, or rekenrek, as a powerful mathematical tool. Building on the idea that children must be able to “see” numbers within other numbers (for example, 7 might be thought of as “5 plus 2 more”), the number rack helps children recognize number combinations of 5 and 10, develop a rich sense of numbers between 0 and 20, and build a powerful set of intuitive strategies for addition and subtraction of both single- and double-digit numbers.

### Supplemental Activity Book

This compilation of student-ready activities builds upon the contexts and learning objectives in Learning to Think Mathematically with the Rekenrek (listed above). Students solve imaginable and accessible problems including cardinality, one-to-one relationships, part-part-whole relationships, and subitizing.

### Activity Book

Ten activities along with an introduction to using the rekenrek or number rack. Includes correlations to the Common Core State Standards.

### Build Your Own Number Rack

#### Materials Needed

• 1 piece of mat board, 6" x 3"
• 2 black pipe cleaners
• Tape

#### Instructions

Along the short side of the mat board cut two small notches one inch from each edge. Thread five white beads followed by five red beads onto each pipe cleaner. Place each pipe cleaner onto the front of the matte board and fold the ends into the notches and around to the back. Secure pipe cleaner ends with tape.

## Acknowledgements

The Number Rack app was made possible by a generous donation from Dr. David Moursund.