Once your teenager gets a grip on credit, introduce them to the flip side -- investing. After all, that's when they extend the credit and collect the interest. Since your teen may have too much money collecting no interest in a checking account and probably writes few checks, the best way to start is with a money-market account on which they can write checks.

From there, introduce them to simple, set-term investments like savings bonds and certificates of deposit. Though returns from these will be meager in today's market, they serve an important lesson and will build their confidence about investing.

From there, introduce them to the stock market, but not as a prelude to picking stocks. Instead, advise them to get into some diversified mutual funds or a solid index fund.

Some of the stock investing games available on the Internet are a fun and educational way to introduce a teenage to stocks. Money.com offers just such a game. There, anyone can sign up and run his or her own investment portfolio -- with simulated cash, of course.

Once you get your child to understand the ups and downs of the stock market, you've probably accomplished all that you can reasonably hope for. In today's fast-buck market, lessons in stocks are available on demand.

Next: Take the test!