A professor in an Englsh university took a year off of his regular duties to vist a university in the States and another in Canada. When he first entered the lecture hall at the American University he said "Good morning class." expecting that the class would reply "Good morning professor." just as they did in England. He was startled at receiving only one "Yo, hiya prof!" in response. Months later he entered the lecture hall in a Canadian University and said "Good morning class." The entire hall of students leaned forward and wrote "Good morning class." in their notebooks.