If you are interested in reading more about it here are a few links:
Dylan Williams-Practical ideas for Formative Assessment
https://traintheteacher.me/2015/06/25/6-ways-to-make-no-hands-up-work/
http://www.ascd.org/publications/educational-leadership/mar14/vol71/num06/The-Right-Questions,-The-Right-Way.aspx