In the past I have worked solutions on the white board for the students. Then I hope that the students will be able to do slightly different problems. The aim used to be that the students would understand the general strategy for solving the problems. However, it is not clear that the weaker students are able to do this.
So in a lecture I tried to explain the general method for solving problems involving discrete probability distributions.
I got an email from a student who claimed this approach helped them do problems.
I was influenced by the book "How to Solve it" by Polya.