Speaking Native
One of the problems we're bound to face is students speaking in their native tongue. One solution that seems to be working for me is to have the students repeat an English sentence 10 times. In my class there's an English sign that says "I will not speak Korean in class." Of course the kids ignore it, but when they do, I have them repeat it 10 times. If they mess up the sentence once, ex. "I will not Korean-speak in class." they have to start again at #1. The next time they speak Korean in class, they have to repeat it 20 times. Not many students have to repeat it twice. If you don't like that sentence, try getting them to repeat a long sentence from a lesson you are currently teaching, or a tongue-twister.