Marilyn Kourilsky can spot a potential entrepreneur when he is still three feet tall and sledding down the nearest snow-covered hill.

Kourilsky, a University of California at Los Angeles economist, who for 10 years has taught such concepts as supply and demand to children, says that persistence is the most essential quality in children who display an enterprising bent. "Youngsters like this," says Kourilsky, "will take an idea like selling calendars, and if they don't make money, they say the idea didn't work. They detach failure from themselves personally and just go on to another idea. If you see this quality in action, you can pinpoint entrepreneurial potential at an early age."

Although nearly a quarter of all kindergartners have that quality, says Kourilsky, only 5% of teenagers retain it. "Many of my colleagues believe that the nature of the school experience wipes out tenacity," she continues. "In our school system, for instance, you take a test once, and if you mess up, you've failed.It's a high-risk situation, and you only get one chance to get things right."