I’ve seen many people who barely use body language while talking. It’s really important to use this tool in order to engross the audience. A teacher should definitely practice it. As the Prophet (SAW) used to do..
Narrated Ibn ‘Abbas:
Somebody said to the Prophet (during his last Hajj), “I did the slaughtering before doing the Rami.’ The Prophet beckoned with his hand and said, “There is no harm in that.” Then another person said. “I got my head shaved before offering the sacrifice.” The Prophet beckoned with his hand saying, “There is no harm in that.”
Prophet (SAW) didn’t move a lot while talking/delivering sermons etc. His hand moved and the face gave expressions. Descriptive enough, yet decent.
So, do use body language while having a conversation/teaching. But keep it balanced. Bot too much, not too less.