A Commonplace Book

Dear Miss Manners:
   My home economics teacher says that one must never place one's elbows on the table. However, I have read that one elbow, in between courses, is all right. Which is correct?

Gentle Reader:
   For the purpose of answering examinations in your home economics class, your teacher is correct. Catching on to this principle of education may be of even greater importance to you now than learning correct current table manners, vital as Miss Manners believes that is.