Try Socrative as a plenary activity.
Go to http://www.socrative.com or download the Socrative Teacher/student app from the iOS or Google app stores.
Socrative allows you to create a simple ‘Exit ticket’ with no set up required. Students join the unique room and answer the pre set questions, whilst the teacher monitors the classes progress from their screen. The answers provided can be downloaded to allow the teacher to plan their next lesson based on knowledge gaps in student responses.
Download the Socrative user guide and try it in your next lesson.
(Image from Socrative.com)