I created this Stoplight Assessment tool to use for formative assessment. I used it primarily in math last year.
At the end of the lesson, students wrote a quick note to me on a sticky note about how they were doing with the concept and put it on the correct spot on the stoplight. It makes a really quick and easy way to get a snapshot of how the class is feeling before you decide to move on to something new.
To make your own, just cut out red, yellow, and green circles (I used scrapbook paper) and arrange them like a stoplight. Then grab the freebie labels from my TPT store, print, cut, and attach!