The 'Before' and 'After' system can work well for coaching. But good teaching is not necessarily coaching students to produce better results in tests. According to me, a good teacher will help students gain an interest in the subject, appreciate the subject better which in-turn helps you perform better. A student is capable of flunking in-spite of being taught well.

In my opinion teachers should be assessed by parents and the management by having a system where every now and then parents are allowed to be part of the class.