It's the time of year for students to go back to school, and it's time for me to go back to school legends.

The rigors of gaining an education, especially taking tests and writing term papers, have inspired an endless flow of legends. There are stories about professors who trick their students into thinking that there will be no pop quizzes, and ones about the ways students try to outfox their profs.As a college professor, I thought I had heard every such tale. But readers recently sent me a quiz story and a term-paper story that I hadn't encountered before.

The classic quiz story tells of a professor who said he was about as likely to give a surprise quiz as he was to enter the classroom through the transom above the door. The students rested easy - until the morning when the professor actually climbed in through the transom, quizzes in hand.

The new quiz story came to me from a boy in Palo Alto, Calif., who neatly printed it on a piece of loose-leaf notebook paper, beginning "Hey Jan!"

When his father was in college, the boy says, he had a journalism professor who promised that he would never give an unannounced quiz.

One day, though, the professor surprised the class with a quiz. When the students protested that he hadn't announced it, the prof insisted that he had.

He had run an ad in the local newspaper that read: "Unit Quiz Today in Mr. McDonald's journalism class, 3 p.m."

"Don't say this isn't true," the boy concluded his letter, "because it is. My dad told me so."

How can I cast doubt on a boy's trust in his father? I'll accept that the story is true, although I would very much like to see a copy of the actual newspaper ad. Surely someone in the class must have saved it.

True story or legend, there's clearly a motive in the journalism professor's gimmick. Besides emphasizing the obvious lesson that students should always be prepared for a quiz, he also must have been trying to train them to read the newspaper closely, paying attention to every detail.

So this story, though said to be true, still seems legendlike. And it has an educational purpose, much like a fable that concludes with a moral.

In the classic term-paper story, the professor is a notoriously hard grader. His students are used to getting Fs, so when he finally awards one paper a B minus, the lucky student gives the paper to a friend who is taking the professor's course the next semester. The paper is submitted a second time, getting a B, and a third, getting a B plus. The fourth time the professor gives it an A, adding: "I keep reading this paper, and it keeps getting better and better!"

Another similar story about term-paper capers was sent to me by a northern California insurance executive, who remembers it from his days as a student at Occidental College in Los Angeles. "The legend had to to with the `crib' files of old exams and ready-made term papers kept in each fraternity," he says.

A student rummaged through his frat's file and found an appropriate term paper, one nearly 20 years old. He typed a title page and submitted the paper - not noticing that its author was his professor, who as an undergraduate had been a member of the fraternity!

"But the student got an A plus on the paper," the executive says, "with this note on the title page: `This paper got only a B minus 20 years ago. But I always felt that it was worth an A plus!"'

I can almost believe this one, in spite of the odds against such a coincidence. Students, I have found, have amazing recall when it comes to the times their professors deprived them of the high grades they deserved.

If only those students would remember the course material as well!