So I ran across a set of red, yellow, green dot stickers last week at Mighty $. I use dot stickers a lot, but I have never found a set of the 3 stop light colors until now.
I have the cups for groups. The idea described by @druinok here and here works very well. My issue, I have desks and there is simply no room for the cups to communicate the groups progress – someone is constantly knocking them into the floor.
My idea is to create stoplight cards for each student, including a paper clip to indicate their color of understanding.
These can be kept in the front pocket of their INBs. Student can quickly grab them out and place on the corner of their desk. As I wander the room, I can easily spot anyone who is stuck on red, has a question on yellow or whether to not interfer with the progressing student on green.
As a pinch card, students ca self-assess by to moving their paper clip or pinching the appropriate color and hold up their card for me to scan quickly.
There are enough stickers to create 100 cards. With a set of index cards, I can have a nice multi-use formative assessment tool for only $2-4.