Was trying to find some sort of digital "exit ticket" where students could respond to the lesson and give you feedback as to how much they have learned.
This product appears to do it and much much more (dont they all). There is a Price Plan if you want to go the "whole hog" but you do get some things for free - https://dl.dropboxusercontent.com/u/7336564/WEB2.0/Exit.png
Students can complete quizzes or questionnaires for their exit ticket. Students can do this on any connected mobile or desktop device. Some impressive storage and displays of results.
Website has lots of good help features and reviews