One of my favorite things I do with my classes is play a game where each class gets a point each time they catch a mathematical mistake I make, either in an example I do, or a classwork or homework I give them. I tally the points in a corner of the board, and every few weeks the class that has found the most in that period gets a delicious prize.
I started the game with the goal of increasing engagement and normalizing error with my students. What I didn’t expect was the difference it would make in getting students to pay careful attention to the precision of language that I used. I gave one class a point last week during an example when one student pointed out that “50% of the data is greater than the median” was actually not true — 50% of the data was greater than or equal to the median. I got a hard time this week as my students figured out that scatter plot is two words, but I had a habit of writing it as one.
It’s small, and not every student thinks it’s cool — but it’s one unexpected way I have my students attending to precision (CCSS.MP6) this year.