Teach a man to fish, and he'll eat for a lifetime. Anyone who has never made a mistake has never tried anything new. People cannot learn without changing. The only person you can change is yourself. People learn better when they are happy.
Language learning is a long, straight staircase.
Language learning is a walk through a jungle. You can speak English perfectly if you just try hard enough. A classroom's most important resource is the people in it. Everything you know you learned from someone else. Every teacher is different, and every student and every class is different as well, so no single lesson plan can solve all the problems.