I did a WODB (Which One Doesn't Belong) and it worked effortlessly

Today I put up my own WODB on the board (I couldn't find a scatter plot collection I liked on wodb.ca unfortunately) and had the students identify which doesn't belong and write their reason down. I did this in place of/as my starter for class today.

I don't know of a decent way to make these graphs electronically, so if someone knows of a tool (all I can think of is GeoGebra) let me know.

Anyway, it went swimmingly. The most common answers were A and D. Here are some of the reasons from students:

Answered A

Answered D

Students used some clever ways of describing things which was awesome. They knew that something was different about D, but had forgotten the word for a data point that is drastically different from the others.

For both of these it was great to guide the discussion from colloquial words to more mathematical language. For instance, on A, some students said it was "positive." I asked "What is positive about it?" or "what do you mean 'positive'? These other ones are about the x-axis." We drilled it down to it having a positive correlation or positive slope.

Those who answered C had some interesting ways to describe a weak correlation - usually by just saying it was "more scattered" than the other ones. We were able to formalize that phrase a bit more too. Awesome!

Answered C

Unfortunately no one picked B. I was bummed about this, but I can see why. When I asked students why they didn't pick B, they said things along the lines of "There was nothing special about it" or "It was perfect." I guess "having a strong negative correlation and no outlier" really doesn't slip off the tongue...

Anyway, great activity. Thanks to all the people who told me about this (half of the presenters at the NCTM conference) and especially Mary Baurassa for threatening me for failure to follow through - oh and for running wodb.ca.

I'm planning on doing another tomorrow with functions (we're reviewing everything from the year.)