[Denis DNT]

It's very hard to say to which extent grammatical terms should be taught considering the fact that even the word 'verb' is a grammatical term. Can we really avoid explaining these terms even if we wanted to?
I recently ran into a problem in my class because a teacher before me had taught the rules for identifying long and short adjectives basing on the number of syllables. The students were saying 'stupider than... the stupidest...'
If my colleague had simply mentioned to them when they were learning the rules that some adjectives with two syllables could be used like long adjectives, it would have saved be quite some trouble. I think a few of them still doubt my 'contradictory' explanation.
Considering the way they accept and stick to rules, I think the better way is to let rules come with the exceptions in one package.