Here is a quick story. A faculty member came to me last week disappointed about the introductory physics students’ lack of understanding with regard to electric potential. Let me call the faculty Beta, because I think that would be a cool name. Beta was disturbed that the students didn’t get potential and it was covered last semester in the first part of the course.
Beta also said, “and electric potential is so simple”. My reply was to show Beta my favorite 3-d puzzle. I think it is called a snake cube. Basically, it is a set of 27 wooden cubes attached together in some fashion that allows it to be arranged in many different ways. The goal is to get it to be in a cube. I showed Beta that it was a simple puzzle and I showed Beta how to solve it rather quickly. Here is the solution
I then gave the puzzle to Beta. I like this puzzle because it took me quite some time to figure out. This is true for most people (that it takes a long time). Once you really understand the puzzle, it is easy to solve. This is just like physics. For us faculty, electric potential is really easy. The relationship between velocity and acceleration is simple. Adding vectors is simple. But it is easy to forget that these ideas were not always simple.
Warning. This trick really fails on some people (especially some physicists). If you give this puzzle to a set of physicists, some of them have excellent 3-d spatial reasoning and can solve this quite quickly (way quicker than my first time).