Briggsy - you're nearly understanding it....
Yes, all students answer a multiple choice question at the end of the lesson. I take in their exit card and mark their answer with a red, amber or green dot (three minutes to mark a class set maximum). The exit cards are then returned at the start of the next lesson. On the board there are three questions, called red, amber and green. Red and amber ask students to revisit their notes, or a textbook, and iron out an misconceptions, green stretches the most able.
If you look here you'll see an example: https://www.dropbox.com/s/cr21sn8rej7kcmm/DIRTy%20Geography%20-%20HOD%20briefing.pptx?dl=0
You'll be able to see the coloured dots (my marking) and student follow up (slide 4), the original question (slide 1) and the follow-up question (slide2).
Hope this helps.