We read the first three acts of The Crucible before winter break and were coming back in January to read the fourth act (in Oregon, the semester ends at the end of January). I wanted a review of the plot before we tackled the final act.
So I created 18 multiple choice questions on the major plot points of the first three acts and grouped them in pairs as nine Google forms that wouldn't let them go on to the second question until they answered the first correctly.
Then I set it all up as a scavenger hunt using QR Codes to link to the Google forms. Students who had smart phones and a data plan formed groups with those who didn't. Then groups used their phones to scan the codes and answer the review questions.
Most of the codes were posted in the school building, but my personal favorite was the one I posted across school grounds by the football stadium.
The students loved walking all the way over there.