Let’s MOD Math Games App (formerly Polyup)

Let’s MOD is a free computational math game where students explore number operations, functions, and algorithm.  You do this in a virtual world or “mod” machine.  Some machines are created for you, and you can create your own.    Let’s MOD can be used on all types of devices, whether as an app or desktop application. Learn about how it works and get tips and tutorials for how to use it in the classroom.


Let’s MOD provides students with visual manipulatives that enable them to think about math in a computational way.  So the focus is on analysis in problem solving in which students develop skills in:

  • pattern recognition
  • decomposition
  • abstraction
  • algorithm design

How It Works

Each game or “Machine” typically consists of four to six problems called “Mods”.  Each Mod is visually represented as a computer chip on a board.

Let’s MOD  is designed for use by classroom teachers, who can assign a Machine with groups of problems to their students.  Many pre-made machines are available at different grade levels. Teachers and students can create their own machines and share them.

To solve a Mod, you manipulate the numbers and math symbols to create a “PolyScript” equation.  You click on the Poly character to run your script and tell you if you provided the correct Mod — equation to solve the problem.  More complex Mods often require multiple results in a specific order.  And the most complex mods use variables and functions.  This video illustrates how it works:


Tips and Observations

  • Make sure you can solve all of the problems in a machine before you assign it. I observed that a few machines just looped through the same problem continually so I could never solve all the problems in a machine. And some seemingly easy problems are very complex. Know in advance how to address that.
  • Before starting a Mod, suggest to students that they remove all symbols and numbers that are not fixed in place. (Those bordered in black are fixed.) This reduces confusion when initially manipulating an equation.
  • Polyup has partnered with Curriki.org to create free lessons built around Polyup machines. Most of these lessons are for elementary students. But new ones are being added.