Coin Sorters by Heather_M_Miller

Last crawled date: 3 years, 2 months ago

In lower elementary, students need to learn to count money, United States coins, in particular, are difficult because the size does not indicate value. Confusing things even more, the dime (10 cents) is smaller than the penny (1 cent). In this project based learning, students are asked to deal with the most common United States coins: penny, nickel, dime, and quarter. Students are to use a ruler to measure the coins’ widths, then create a device that allows a handful of coins to be sorted, using gravity. In the real world, banks, tellers, cashiers, PTA Treasurers, kids running the school store, kids with lemonade stands – they all sort large amounts of mixed-up coins so that they can be bagged and taken to the bank. To get gravity to work properly, there needs to be some kind of inclined plane (slope) or levels, or some mechanism to allow gravity to pull the coins from the mixed group, by size.
One example design is an inclined plane with holes for the coins to fall through the inclined plane into an added cup or bag. A second example design uses pins to knock the coin off the front of the inclined plane, into a cup or box. For the 3D print, students should be mindful that “thin” is not necessarily best because of the raft, and warping of thin flat panels. The device will stand better if it is thicker, and thicker allows for waffle/hollow spaces.
Because I only have a MakerBot Replicator Mini, I had to copy my design and split it, printing it in two batches. I possibly could have turned it vertical and printed it in one run. My first print of the top of the design with holes sorted the dime and penny properly, but it was too thin. Some raft got stuck, and it has to be held or lean against something to stand it up. I thickened it up in the designs I included.
Remember, since the idea is to create a STEM experience for the kids, these sample designs are really not designed to be “copied” but to serve as inspiration for the kids to see what a gravity sorter might look like.
‘To make it a different challenge, have the kids use only the measurements from the US Mint webpage.