Today’s teens expect to make big bucks when they reach adulthood, according to a recent survey. But what they know about personal finance won’t help them live off what they most likely will earn.

That disconnect is part of the reason why there are so many adults in credit card trouble or struggling to manage mortgages on homes they can’t afford.

American teens believe, based on the career that interests them the most, that when they get older they will be earning an average annual salary of $145,500, according to the findings of Teens & Money, an annual survey by Charles Schwab & Co. and the Boys & Girls Clubs of America.

The fact is, only about 14 percent of U.S. households have incomes between $100,000 and $200,000, reports the U.S. Census Bureau. The median household income in the United States actually is $46,326, according to the latest Census figures.

It’s fine that teens have hopes of earning high incomes, but just in case things don’t turn out as they plan, you’ve got to teach them to live within their means.

Nearly two-thirds of teens surveyed by Schwab said they were prepared to deal with personal finance issues after they graduated from high school. The majority said they were knowledgeable about money management, including budgeting, saving and investing.

But when these 13- to 18-year-olds were pressed on the specifics of personal finance, many didn’t know much at all, this survey shows.

Fewer than half of the teens surveyed knew how to budget. Others didn’t know how to pay bills, how credit card interest and fees work or whether a check cashing service is good to use (it’s not).

Yet teens certainly know how to spend. They have no problem using credit. That we’ve taught them well.

Teens were more likely to have a cell phone than a savings account. Although 88 percent of them said they don’t like the way it feels to owe someone money, almost a third (29 percent) have incurred debt (close to $300, on average).

The surveyed teens say they aren’t being taught basic money management by the people who have the most influence over them – their parents. Only one in four said their parents or guardians are training them by giving them experience budgeting, spending and saving money.

Your children will have a better chance to live within their means as adults if you spend time while they’re young showing them how to handle money. Teach them how to create a budget. If you don’t know yourself, start by downloading a budget form I’ve created at www.washingtonpost.com/business. You also can go to a new Web site that Schwab has created at www.schwabmoneywise.com, which has a number of tools.

You will train your children well if you rebuff many of their constant consumer demands. Right now what many know is: I want. Mommy and daddy give. It will be hard for them to depart from that habit when they’re grown.

As Carrie Schwab Pomerantz, chief strategist of consumer education at Schwab, says, “Teens not only want the keys to the world of adult finance, they are actually looking to their parents for driving lessons.”