Our local school district had our annual K-6 Science Expo yesterday. It was a blast!

Surprising no one, I sold raffle tickets to help keep the expo free for all students. Surprising everyone (or maybe no one who reads this), I brought my Lego EV3 Mindcub3r to make the raffle ticket table a little more interesting.

Funny things happen when you use a robot to solve Rubik’s Cubes for hours on end.  At one point my EV3 was misbehaving, so I decided to check the batteries and the poor little AAs were actually hot!  I replaced them, and everything was OK.

The most challenging piece was the mechanism that flips the cube. It has a tendency to slip during the solve phase, and this problem seemed to get worse as the day went on. Being that we were at a Science Expo, the kids and I decided to come up with a hypothesis and then run some tests.

Hypothesis #1: we needed more weight. So we tried adding weight. We added a couple of small pencils. A AA battery. 2 batteries, then 3. Nothing. If anything, it seemed to make the problem a bit worse.

Hypothesis #2: we needed more friction at the point where the Mindcub3r does the flip. So I added a small piece of, you guessed it, duct tape.

And voila! The solve rate went back up to a pretty reasonable 80-90% and, more importantly, the kids learned a very valuable lesson:

Duct tape fixes everything.