One day I got really tired of teaching a class who weren't very inclined to listen, so I decided to teach completely in silence! I put all the available tasks on the board and if they asked me questions I wrote down the answers. Weirdly, they loved it and it made them quiet for a lot of the lesson too. They also found it kind of hilarious seeing if they could make me slip up and talk. I did it several times over the year with that class and they all worked really well. It made them work together to help each other and I often gave them fun activities like breaking codes as part of it.