• Makey Makey (MM) and a simple 3D printed case to hold MM
• Alligator clips and alligator clips with pigtail 
• A reasonable size of cardboard box 
• Brass fasteners
• Braille for math: Nemeth Code: numbers, dot, and operations; braille for four commands: start, enter, reset and ground
• Option: antistatic wrist strap instead of holding the ground key
• All 18 keys are used in the calculator. Follow the instruction: https://makeymakey.com/pages/remap to do the remapping. Below are the keys in the Makey Makey setting for this calculator.

Front side of the Calculator

Touchpad Closeup 

All wires and MM are hidden inside the box, the top with printed braille and brass fasteners.

 Video of the Prototype 

Remix or connect Makey Makey inputs to this project by Tracy Zhang in Scratch.

Use a keyboard to test the calculator:

• Press “Spacebar” to start the calculator, then listen to the voice prompt
• Press “Enter” after each input of numbers, operations and answers
• To start over during calculation, click the mouse (again, the mouse cursor needs to be hovered over the project screen when click)

• During the operation, the ground key needs to hold the entire time either by touching or using a wrist strap. For right-handed users: use a finger of the left hand to touch the ground brass fastener to complete the circuitry. For left-handed users, the ground brass fastener can be set up to the low right corner in the touchpad. Or use an antistatic wrist strap
• Users read braille, then activate the key by touch the brass fastener of the corresponding braille, which is located at the slight left side of each braille 
• To start the calculator, activate “start” key,  then listen to the voice prompt
• Activate “enter” key after each input of numbers, operations and answers
• To start over during calculation, activate “reset” key

This project was a team effort!

The Ann Arbor team from Makers Making Change is making the case. Tracy wants to thank Evie, who inspired Tracy to make something to help Evie learn math. She is a beautiful and blinded girl with gifted in music. Here is a video of her singing.