I have just spent 1:20:00 watching the following youTube. The method is brilliant. It can be used in almost every subject. I don't want to spoil the fun of watching it. If you are really have no time, highlight the white area below the movie, I have a summary there which should take about 10 sec. to read.
The students are asked to read a prescribed text before class. During the class, a problem is presented. The students are to remain silence for about 1 minute to think about the problem. Vote the answer. Discuss with neighbour. Vote again. Lecturer explains the solution. Repeat. The important point about these problems are they focus on conceptual understanding, not "receipt substitution".