This post reminded me of the following story:

So far, my only NCTM conference was in Anaheim in 2005. Between sessions I attended the TI workshop on the TI-Navigator™ Classroom Learning System, or whatever they had at the time.

It really is a cool system. You can have students do work on their calculator and wirelessly send you the results. You can give quizzes, get instant feedback and adjust your instruction. You can also display an image and have students interact with it, which we did in the workshop.

To demonstrate linear regression the TI representative displayed some image similar to:

The participants were asked to plot a point anywhere on the bridge’s fence line. These points, as well as their calculator number, showed up on the image. Most of the teacher-participants were very obedient and picked a point exactly on the line. *Somebody* wanted to see what would happen if he picked a point which wasn’t even close to the fence line.

The resulting picture looked like…

The TI guy happily showed us how to find and graph the equation which looked like:

Oops…

After a long pause the presenter said, “That’s never happened before…”

I was starting to feel bad for the presenter when some annoyingly helpful teacher pointed out the point in the corner. Another teacher noticed the calculator number next to the point…

I was quietly hiding my calculator number when the presenter commented on turning something like this into a teaching moment…

Photo from Windsordi.