There are a range of ways to gauge student feedback in your lessons. There are conventional methods such as holding up a number of fingers or traffic light cards. Here are five more sophisticated methods that can be done online. You will obviously need access to the internet – ideally one machine/device per student.
2. Pollsnack
3. Socrative (You will need the socrative app installed on any mobile devices you are using)
4. Flisti
5. Yarp
If you are booking a class set of iPads or a computer room then have a go at using one of the above during your lesson. Maybe focus on planning a couple of hinge questions and use these to assess understanding at that crucial point in the lesson. Watch this short explanation of formative assessment by Dylan William and you will see how student feedback (using some of the above methods) can be so effective:
Learning and Teaching at Abbot Beyne 
I’m going to use Polleverywhere.com in class next week. It’s a nice, very simple way, of taking a live-audience poll. No sign up required. No app. You can make a poll in 3 minutes.
You load the poll on the screen and it auto-updates as learners vote. To vote they go to pollev.com and enter a voting code from the screen. Alternatively, they could text their answer in.
Here’s one I just made: http://www.polleverywhere.com/multiple_choice_polls/D8hkn0MPVCtPi3O