Identifying errors through flawed examples.

Give students an example that closely mirrors the problems you want them to be able to do. Instead of a nice clean example, give one with an error and have the students locate and explain the error. Through the process of finding the error they will develop valuable proof reading skills and it necessitates working out the problem correctly in order to show the error.

Plus, students love when the teacher makes a mistake and if you plan your mistakes to illustrate ideas that are central to your lesson, it can highlight important skill and common errors.