Last week I shared about the informal rulers we made. (Look here.) I also shared about the broken ruler idea, which helps to clear up some major measurement misconceptions that even upper elementary kids still struggle with. (Click here.) I combined both of those concepts to create this task. It takes zero teacher prep, which admittedly, I like a lot.
The idea was that each mathematician got to choose an object of their choice from their desk and place it above their informal ruler in a way that would trick everyone else. In other words, they couldn't line up their object with the first unit like they typically would. They had to choose another unit to line it up with. (This task alone was good for a handful of them who still needed practice lining up the edge of an object with the beginning of a unit.)
Then each child left their object and ruler on their desk, grabbed their whiteboard and marker, and traveled around the room to other desks to record as many measurements as they could.
First off, it was sure nice that I had nothing to prepare for this lesson. Secondly, the kids loved traveling and proving they couldn't be tricked. Lastly, it was pretty obvious who was indeed being tricked, and I was able to have some one-on-one teaching time with them. All in all, a success!