Money ideas, like new foods, are best fed to kids in stages. Gradually teach them tougher concepts - and at 17, give them a credit card. Then you'll learn if they were listening.

Habits adopted at this tender age (like brushing teeth) are likely to last a lifetime. This is also a good time to start an allowance, but learning to stash a portion of the cash is more important than the source of the income, says Laura Levine of financial literacy organization JumpStart Coalition. Use a see-through piggy bank so your child can watch the money physically accumulate.

As 'tweens, kids get the hang of abstract ideas, so they won't feel that they're giving away the money they put in a bank. Learning multiplication will also help them understand how interest works. "Show kids how quickly money can grow, and aim for them to save 10% of birthday and holiday money, allowances and such," says Carrie Schwab Pomerantz, who runs financial literacy programs for Charles Schwab.

Children in middle school understand that money is limited, and they can tell the difference between needs and wants. So put those skills to the test. When back-to-school shopping rolls around, give your kid a budget and let her decide whether she'd rather have, say, one pair of designer jeans or five Value Village T-shirts.

One out of five 16-year-olds works a part-time or summer job. If yours is one of them, offer to match dollar for dollar any earings he saves for retirement. If he needs convincing, show him how just $500 invested at an 8% rate of return can grow to $15,000 by the year 2051.