How to learn grammar
Teaching English also means teaching grammar. Generally speaking, there's the lesson, learning the tenses and then exercises. The problem with exercises is that when students have to write or formulate a sentence orally, they feel stuck, because they've had too many 'crutches' before with gap-filling exercises.
What's more, after 12 years, pupils rely totally on French and they model English on French: a fatal error! What I recommend is to explain without taking into account the French system. There is an English system, the English language has its own way of thinking about the world, so the English language has its own grammar, it's an autonomous way of thinking that has nothing to do with French.
Example: I didn't dance, I don't say "I didn't danced" because in the sentence: "did" is the element that refers to something in the past (no need to add an "ed" at the end of dance) and the "'nt" refers to negation. "Why do I put an "s" in he she or it? He, she, it are articles that refer to an individual in a group of other people, so you reinforce this idea by putting an "s" in your verb.
