[Denis DNT]

I have met colleagues who stand for the opinion that in a good ESL class, the students should be able to make the rules themselves with very little guidance from the teacher. Like Kisito mentions, they say that when enough practice on the language structures is done, students will unconsciously get a rule to that structure.
Well, right as long as the structures are simple ones.
I think the biggest danger in teaching rules is teaching wrong rules. It gives the next teacher a double uphill task. Students who have not been taught any rules at all are better than those who have been taught wrong rules.