This past week I used the Mtbos resource of Which One Doesn't Belong?
I feel like this a a low floor, high ceiling task that forces students to explain their reasoning--which I need to find more ways for students to practice.
Before giving the students the homework, I gave them the following list--7, 21, 27, 42 and we practiced finding which number didn't belong. I randomly wrote those numbers down, and I am lucky it worked out really well. The students were able to come about with about 10 different ways to explain a number that didn't belong.
The homework they got is below.
I asked them to think outside the box--yes 16 is the only even number, but I wanted them to dig deeper than that.
I plan on sharing their various responses with the class hoping that all students can be more creative the next time I give them homework like this.
If you would like to use this, you can download the pdf here.