Professor Rob Weagley isn't surprised when he sees tears in a student's eyes during his class on credit cards.

Weagley teaches consumer economics at the University of Missouri-Columbia. The tears tell him he's found another young person who should have taken the class sooner.

He'll take the student aside for a "ceremonial cutting up of the credit cards" and advice on how to get back on track.

Moms and pops across St. Louis this summer are kissing kids goodbye as they head off for their first real taste of adulthood, be it in a college dorm, the military, or their first job and apartment.

Most will do fine. But some will slide into a swamp of debt.

Weagley chairs the department of personal financial planning at Mizzou, and thus has ample experience with youthful profligacy.

Two-thirds of college students graduate with student loans, and some of them borrow stupidly. That's grist for another column. For now we'll focus on young people falling into debt for things beyond tuition and books.

Starting a new life means making new friends in a strange place, and that's tough for any 18-year-old. Sometimes kids of limited means get into trouble trying to keep up with richer friends, says Weagley.

"They're trying to live a life that's somebody else's," he says. It leads them to spend too much on clothes, entertainment or a car. The fraternity and sorority system, with its emphasis on social life, can make the temptation worse.

"Their ego is tied to what they own, what they wear, what they do. It's so hard for young people not to feel like that because they learn it from older people," he says.

Plastic makes the splurging easy, yet hard to track. So, consider the kind of plastic in a young person's pocket.

A debit card pretty much limits spending to the amount in your checking account. Banks can charge fat overdraft fees for bounced checks, but not for debit card overdrafts unless you specifically sign up for overdraft protection.

By contrast, a credit card is a license to plunge into hock, at interest rates averaging 14 percent. It can be a fast track to bankruptcy.

The good news is that parents now have a lever over their profligate progeny. Under a 2011 law, people under 21 must have a parent's consent to get a credit card unless they can show proof of adequate income. That rules out most college students.

Before signing up, Mom and Pop should peer deeply into the soul of their young genius. Is he or she responsible enough for credit?

On the other hand, dads like Weagley and I worry about the lonely road scenario. What if my daughter is stuck on a lonely road with no cash and no credit card? Our kids had credit cards in college.

Getting a job on campus helps in ways beyond money, says Leanna Fenneberg, vice president for student development at St. Louis University. Studies show that kids who work up to 15 hours a week on campus do better academically. They learn to use their time better, she says.

The same can't be said for jobs off campus, perhaps because real-world bosses grant no slack for things like final exams.

Parents should put their own names on a student's checking account, says Weagley. It lets them see where the money is going, and it also makes it easier to send money electronically.

A budget, drawn up in advance, can also help, says Weagley. In Missouri, high school students are required to take a one-semester course in personal finance, learning budgeting, credit and the like.

The freshman year of college is fairly sheltered; kids live and eat in a dorm. Moving out to an apartment brings extra costs, such as travel and utilities, that hit young people by surprise, says Weagley.

Many colleges, including Mizzou, have an emergency small-dollar loan program for students at interest rates of "low or none," says Weagley. Mizzou's program requires students to go through the student counseling center before getting the money.

Of course, frugality is best learned long before a kid gets loose on campus. I started giving skinflint lessons when my daughters were in grade school.

I was really good at it. I'd whine when they'd ask for their allowance, opening my wallet to show the few scrawny bills inside. "Four dollars! Do you need all four? Where do you spend it all?" I'd ask.

One day someone backed into my passenger-side car door in the parking lot. A teachable moment! I refused to get it fixed for months, even though the door wouldn't open. My kids climbed in and out the window.

"We'll have to save up until we can get a new door," I told them.

I complained about the price of everything. My daughters thought they were the poorest kids in Clayton. They walked to school past the fancy cars in the Clayton High School lot.

The lesson stuck. My oldest daughter paid off her mortgage at age 33 — a chip off the old cheapskate.