My teacher in (subject or school here) taught me to write this way.

A: On behalf of all teachers everywhere, I apologize for the mistakes of my colleague(s).

In many areas of life, "house rules" vary. I prefer the Chicago Manual of Style, but others prefer the Publication Manual of the American Psychological Association. However, there is no class rule in academe that permits plagiarism. Any teacher in the U.S. who has suggested you copy from the encyclopedia—or the equivalent for older students—has sinned against the profession. I assure you that he is, at this very moment, circumnavigating the Library of Congress on his bare knees in penance.