One tool that I have started using only in the last month, and with great success, is Kahoot.
I learned about Kahoot from a student, who used it in a fun activity. I immediately saw how effective it could be in an educational format. Kahoot is an online, interactive quiz. The quiz is designed by the teacher, students log on (either as individuals or in teams) and answer multiple choice questions. Questions can be timed, scored, and discussed. There is also a survey mode and a discussion mode.
This tool is great from a few angles. The students get really involved. There is something about bright colors and points that gets students going. It is a great way to instigate conversation. The teacher has the power to make the game pause or move on. If you ask a difficult question and students get it wrong, they want to know why. It is a great place to discuss questions with nuance and layers.
The multiple-choice quizzes are a great feature for reviewing reading homework from the night before and prepping for a test. I use Kahoot to start classes after assigning 1-2 chapters of reading the night before.
I find the discussion feature pointless. It only allows for two choices, which is too guided for my taste. I would like it better if the students were able to discuss and input a paragraph that were could read aloud and discuss.
A great strength of this app is that it provides detailed reports. Then, I am able to assure the students that their Kahoot “game” is for a grade, either classwork or quiz grade, depending on the material. This leads to very strong participation and a great way for me to check for understanding. It was also extremely easy to learn. I saw it used in class, went home that night and played with it, and had made my own and executed it at the end of the week.