At the Park Road Primary School (name changed) in Bradford, teachers use a standardized gesture system called Makaton (www.makaton.org).  It's a set of hand movements that teachers and students use to facilitate communication.  Unlike a true sign language, Makaton gestures are used in conjunction with speech because it's geared for English language learners and other students who may need a bridge to spoken English.  Teachers have been trained in it and seem to use it pretty fluently, especially in the younger grades.  Lots of ELL kids use it as well because it seems like it boosts their confidence to participate in a class discussion taking place in English.