To give students an idea about sensemaking in physics, I took a page from Kathy Harper and used pinochle as a way for students to experience what it's like to try to understand the rules of a game when you only see examples of the game being played. After talking about "confusion is the sweat of learning" and how we use evidence to argue our points, I passed out just the first meld from this document to groups and watch them try to figure out the rules. I give hints about how the players only put down cards that will score them points and tell them what a trump is (many don't know!), then pass out the second meld, and then, after a few minutes, the third meld. It's always interesting to see who works with who and whether groups join forces. (I tell them afterwards I want groups to fuse if the going gets tough; we're smarter together than apart.) We then talk through the rules, and once a little has been figured out, it gets easier and easier.
I also told them to evaluate themselves on what they understand now, not on how they felt at the beginning of the activity.
We then debriefed on the reflection activity and started some practice on drawing reflections on plane mirrors.
