# The K'NEX Calculator & Receipt

I'm just starting my Project Based Learning unit with K'NEX this week in my STEM class. My first module is to allow students in small groups to build their own car. Often times students will try and build the biggest car with the most pieces possible. After running out pieces last year and students getting upset, this year I did something a little different.

Each group's car was going to be judged on an efficiency scale. The formula was simple:

Distance Traveled in CM ÷ Cost of Vehicle

In order for students to figure out the cost of their vehicle, they were given an Inventory Sheet with unit prices. After building a prototype, testing it, and making any changes necessary on their vehicle, they were to calculate their vehicle's cost. When confident in their calculations, they would "check out" in the back with me by entering their quantities of each piece (connectors, rods, tires, wheels, spacers, gears, and panels). Finally, they would submit their form and I would print their receipt that is generated by the Google Add On: Form Publisher. I have it set up so I get the PDF filed e-mailed to me currently. (The receipt sample is to the right) Personally, I have them glue these into their journals for reflection and data analysis.

The students could then run three test trials of their vehicle on a ramp. The guidelines are simple: you cannot push it off the ramp and it you can only measure to the spot that it stays on that track (taped lines). After doing the three trials, you take the average and divide that by the cost of your vehicle to get your Efficiency Score. The lower the score, the better your efficiency is!

Feel free to make a copy of the folder and customize it for your use! My students love to see how efficient they can design their car and it got them to think in practical design with purpose rather than aesthetics. True design thinking!

To the left is a copy of an Efficiency Score example. I used the same 0 - 1.5 is High Efficiency, 1.5 - 3.9 is Average Efficiency, and 3.9+ is Low Efficiency. You can adjust that using the conditional formatting in the Google Sheet form as you wish.

Make a Copy of the Folder (Efficiency Score Included)