When Sketchpad is Wrong

Last week we went into the lab to play do an investigation with Sketchpad. The task was to create various polygons, measure the angles in each, and calculate the sum of the interior angles. They were then to formulate a “rule” for the sum of the angles as a function of the number of sides.

Then Sketchpad made a mistake.

“Mrs. B, I know this thing is supposed to be 360. Sketchpad isn’t working.”

I know they’ve “learned” how to name angles in middle school. We talked about it before we went into the lab. Doesn’t matter. I think they think math teachers are just really picky and it doesn’t truly matter.

Then Sketchpad is “wrong”. Then I get to have great discussions with a few individual students.

Then these students get to help those working next to them.

I love Sketchpad.

Formative Assessment?

We were recently going to do an activity that involved finding the formula for the sum of the interior angles in a polygon.

This required that they know that a few terms beforehand. I wanted a quick way to check their prior knowledge. I didn’t want to do a worksheet. I didn’t want to give a quiz.

So we played Simon Says.

Simon says stand up and face the front of the room.

Turn 90 degrees to the right.

Gotcha, I didn’t say Simon Says.

Simon says turn 180 degrees.

Okay, now face the front of the room (only got one or two that time).

Simon says turn an obtuse angle.

… you get the idea. Toss a few fun things in there too. Like: Simon says hop on your left foot.

We laughed. They moved around a bit. And I knew exactly which terms I needed to review prior to beginning our activity.