This lack of basic understanding about money among a majority of Americans has been a consistent finding over the years. Look no further than the subprime-mortgage debacle and loans with teaser rates as an example of how awful things can get when consumers don't understand the financial products they buy.

It is bad enough that most people are not financially literate, but the painful reality is that investor education does not work — at least not much beyond six months.

After that, it is like any other abstract subject taught in a classroom, mostly forgotten.

Academic research has confirmed this. One research paper looked at more than 200 studies, and reached the conclusion that the lessons of financial education are fleeting, and degrade quickly without frequent use.

Nobel economist Richard Thaler has suggested several behavioral nudges that might help; he too acknowledges the limits of teaching financial literacy.

Learning decays rapidly, so whatever we teach high school students is mostly forgotten by the time it's needed. By way of example, Thaler suggests trying to recall what you learned in high school chemistry.

Not that this has stopped states from mandating financial literacy for high schoolers.

The Washington Post reported last week that financial-literacy classes are mandated by 19 states in order to graduate from high school, up from 13 states eight years ago.

This is well-meaning, but without a radical break from how financial literacy is taught, it is destined to be ineffective.

Why? There are a number of reasons: The subject is abstract and can be complex; specific skills deteriorate fairly soon after graduation from high school; the rote memorization and teach-to-the-test approach used so much in American schools is ineffective for this sort of knowledge.

There are some potential solutions for these issues:

No. 1. Hands-on education: Teaching finance is not well-served by the standard format of classroom lectures. Instead, if we want to make students proficient in budgeting, help them understand credit and teach them about investing, a better approach would be a learning experience from real life.

Student-run businesses on campus, and internships at local businesses, or actual jobs in finance do better at showing students how to do these tasks than the lecture-and-test approach.

No. 2. Repetition: Unless financial literacy is constantly reinforced, as we noted above, it fades pretty fast. Core concepts need to be repeated and reinforced after graduation. It is not realistic for us to expect high schools to be able to accomplish this.

Some of the burden for repetition and reinforcement must fall on the private sector, particularly the financial industry itself. More firms need to make a commitment to integrate financial literacy in their client-services operations.

The key is keep the basic concepts of compounding, cost drag, valuations, diversification and cyclicality in front of customers, ensuring that they understand and are familiar with the terms and concepts.

No. 3. How to think: The idea of giving students a list of facts to memorize and then testing them has been shown to be of limited use in real-life problem solving. This approach to teaching is the educational equivalent of fast food.

A complement to the real-life experiences (above) is a more Socratic method of instruction. Rather than mere lecturing, instructors should lead students on a guided hunt for information. Let the students figure out the ideas for themselves, with the instructor as the pilot. This sort of approach leads to harder-won knowledge, which tends to be more durable.

Rather than teaching a body of information to remember, education also needs to give students the skills to think critically, to puzzle through problems, to be skeptical, to ask questions.

Unfortunately, this broader approach to problem solving and independent thinking is rarely on the curriculum, no matter the subject being taught.

Financial literacy is critically important, and will become more so as social programs such as Social Security and Medicaid become stressed.

If we continually fail to provide Americans with the tools to become and maintain financial literacy, we are asking for more of the kind of problematic behavior that contributed so much to the last crises.

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