A tool that I use every week is called Kahoot! It is a game based tool to find out what your students know about a topic. It is multiple choice and the students need to have a device to play (we have 1:1 Chromebooks). I learned about Kahoot a couple of years ago at a CUE conference in Palm Springs. After that I was hooked. I have taught it a couple of times to staff members and other teachers. So far everyone I know who has used it, loves it. Most people can figure out how to use it pretty quickly. It's very user friendly. I think I started to use it within a week of learning about it. I have used this in my classrooms (2nd and 3rd grade) and in staff meetings to talk about a subject. I always use it as a tool after the learning occurs, but I have also seen it used as a "What do they already know?" tool.
The strengths of Kahoot are: