I am one of a small English/French group of friends who meet once a week to help each other with language. This week we were transating a French text - the literal translation was "while I will be enjoying myself, they will be writing their boring essays". We said that the correct English would be "while I am enjoying myself, they will be ..." - in other words, we wouldn't use the future tense after "while". We all knew this is correct, but we couldn't quote the rule, and one of our French friends, a bit of a pedant herself, really wants to know WHY. Can you help?