Having survived the teenage years of two children, I know how foolhardy it is to offer advice to 18-year-olds. But, after more than three decades of teaching, I do have a few tips for college freshmen everywhere:

Make sure you are in the class you signed up to take. A week spent trying to figure out why the person you thought was your math teacher keeps talking about Renaissance art is a wasted week — for both of you.

During class, do not: a) beat out a cadence on your desk while the teacher is lecturing; b) sigh audibly more than three or four times during a class period; c) check your watch more than twice during the hour. Do: a) practice a look of genuine interest in the lecture or discussion; b) nod in agreement frequently; c) laugh at all (or at least most) of the professor’s jokes.

Do ask questions if you don’t understand the professor’s point. Do not, however, ask any of the following: “Will this be on the test?” “Does grammar count?” “Do we have to read the whole chapter?” “Can I turn in my paper late?”

Finally, ignore the looks of scorn and amusement on the faces of the upperclassmen and -women; remember that next year you will be able to laugh at the mistakes and confusion of a new freshman class.

Carol Berkin, a professor of history at Baruch College and the author of the forthcoming “Civil War Wives,” has been teaching since 1972.