Rotate the Cell Phones

One of the things I am working hard at this year is making things more clear to students. I want them to understand concepts and why they are important and useful. Of course one issue with teaching computing is that experienced people are used to thinking in the abstract but beginners are not. So tying theory into physical activity can be helpful. And if you can use something students care about even better. I was pleased to discover a new visual aid today that I think worked well.

I was working with a simple project – rotate the values in a series of textboxes.

Take what is is the first box and move it to the second, the second into the third, the third into the fourth and the fourth back into the first.

Experience tells one to save what is in box 4 in a temporary variable so you can copy it later and not lose it. Students sometimes have trouble visualizing this in their heads and I often see projects were a value is lost for each rotation. In the past I have used classes of soda (pop, tonic, soda pop) and asked students about how to swap the contents. Today I didn’t have any of that (poor planning perhaps) and I was talking about more than two items to swap. Fortunately an answer was at hand.

The new school policy this year (let’s ignore if it is a good one or a bad one for now) is for all students to place their phones in a rack in the front of the classroom when they arrive. Teachers can of course tell students to keep and use the phones when educationally appropriate. In any case I had a rack of phones to use. Four phones in the bottom four slots in the rack. How convenient!

I asked a student to come up and show me how he would rotate them though the slots in the rack. Interestingly he tried to explain it to me but I insisted he show me.

This turns out the be an important step because it forced him to think for a second. The answer was there but not clear and solid until he was forced to move physical objects. After a pause he picked up the first phone and moved it out of the way – to an empty slot in the rack. Rotating the rest was easy after that.

Watching the students duplicate my example (from only the running form and explanation) is seemed like students understood the concept of the temporary variable better than usual. We are teaching a visual generation for sure. I wonder if the cell phones were an extra incentive to watch? Regardless this is a visual I plan to use again. When we cover sorting for example.