In my last post I wrote about hinge points. Kate has just posted a way she uses index cards in lieu of clickers in her class. The only thing I would change is putting each set on a binder ring. Just seems easier to keep them together.
Now all you need to do is design in a hinge point question. Decide what percentage of students need to get this question right. Calculate the correct responses and you now know whether to move on or try again.