Design a Coin Sorter

Alright young engineers, it's time to think creatively about this challenge. Many of us have seen the Coinstar machines at supermarkets that sort and count your spare change into "paper" money. But how do these machines work? Better yet -- how could these machines work?

CRITERIA -- to design a device to sort common U.S. coins (pennies, nickels, dimes, and quarters). 

CONSTRAINTS -- the materials that I will provide and the fact that all of your coins must go through the same slot (either one-by-one or all at the same time).  In other words, your "sorter" cannot just be a piggy bank with different bins for pennies, nickels, dimes, etc.

MATERIALS -- I will provide for you: index cards, paper, egg cartons, cardboard, small paper cups, tape, glue, staples, scissors, and rulers.  You may also bring in any materials that you have available at home to help.  You may NOT go spend money at the store to purchase materials.  Tis the season for giving, but spend your money on something (or someone) else!

Here is a list of physical properties of coins we brainstormed in class to help you think about how this might work.

• color: silver or non-silver
• size: thickness, diameter, circumference
• image (president on front and landmark on back)
• ridges or no ridges
• composition
• mass or weight

Good luck, engineers!