There are good reasons for not using gestures most of the time. Many students would have great difficulty understanding you if they closed their eyes. They read not only gestures but all sorts of body-language, especially expressions and it is surprising how much they understand from these clues. Most of this information is in fact unwittingly provided by the teacher and in fact it should be rationed according to the needs of the moment. Indeed it can be important to eliminate gestures if you wish to prove to yourself that a student has really understood what you have said. For example when a teacher wants a student to ask questions he often uses prompts

S "Where does Mr. Chevalier live?"
T "He lives in Versailles. - and Yvette?"
S "Where does Yvette live?"
T "She lives near the Louvre. - and you?"
S "Where do you live?"

The student has slipped up because the teacher didn't make the gesture of pointing (however vaguely) to his student. The student just replaces the word "you" in his sentence as he did with the preceding prompts. This does not mean that the teacher should have made a gesture; on the contrary he should abstain from gestures to make the student listen and ideally his correction technique for the above error will be verbal and not simply to repeat his prompt with the "missing" gesture. e.g.:

T "Just a minute. Yvette again."
S "Where does Yvette live."
T "She lives near the Louvre. - and ME?"
S "Where do you live?"
T "I live in Montmartre. - and YOU?"

With a bit of luck he'll get it right this time because he's already asked the "you" question and will be expecting something different so will stop to think.

Gestures are, however, a major tool when it comes to communicating with beginners and near beginners. Clarity is essential and it is surprising how ambiguous they can sometimes be. Even the simple gesture of pointing at oneself or at your student does not always get the same response - it depends on the prompt and also on the "mode" the student is in. If he is in "Adapt" mode then the teacher would point at himself and say "and me?" to elicite a phrase beginning "you ...". If the student is in "Repeat" mode he will point at himself and say "you" to get the same result. Most teachers have trouble initially at pointing to themselves and saying "you" or pointing at the student and saying "I". It seems to go against the grain at first. However a wrong prompt here can actually get the student to believe that "I" means"you" and "you" means "I" in an extreme case.

Be generous with your gestures. Anglo-saxons are not very good at this, we are one of the few races to be able to talk with our hands in our pockets. Thus when we have to try them they tend to be inconspicuous little movements which don't really work. If you are introducing the word "big" then do it with an arms stretched gesture as wide as you can reach.

Be imaginitive too: A pointing down to the ground gesture usually gets over a concept of "here" but it can also be used to indicate a kind of genaralised "now" if you are introducing the word "today" for example.

A circular gesture taking in all class members will get over "we" when you have used the word as a prompt and your (French) pupils think you have finally broken your own rule of speaking only English in class and heartily agree with you "Oui, Ah Oui!!"

Mark Yates 2000