Date: Fri, 28 Aug 1998 21:12:38 -0400
From: Alex Bogomolny
1/0 is undefined or, as you put it, cannot be done.
I can't think of a reason for a math teacher to blurt something so stupid, except for the obvious one. Not only there is no reason, there is also no good purpose in saying this. Ask your teacher what might be done with this infinity, what is it good for that he (she) found it necessary to introduce it?
I would mention the incident to your parents. The teacher might not be very competent which is a reason for concern.
All the best,