The chairman of Sun Microsystems was up against one of the most vexing challenges of modern life: a third-grade science project. Scott McNealy had spent hours searching the Web for a lively explanation of electricity that his son could understand. "Finally I found a very nice, animated, educational website showing electrons zooming around and tests after each section. We did this for about an hour and a half and had a ball-a great father-son moment of learning. All of a sudden we ran out of runway because it was a site to help welders, and it then got in-to welding." For McNealy the experience, three years ago, provided one of life's aha! moments: "It made me wonder why there isn't a website where I can just go and have anything I want to learn, K to 12, online, browser based and free."

His solution: draw on the Wikipedia model to create a collection of online courses that can be updated, improved, vetted and built upon by innovative teachers, who, he notes, "are always developing new materials and methods of instruction because they aren't happy with what they have." And who better to create such a site than McNealy, whose company has led the way in designing open-source computer software? He quickly raised some money, created a non-profit and-voila!-Curriki.org made its debut January 2006, and has been growing fast. Some 450 courses are in the works, and about 3,000 people have joined as members. McNealy reports that a teenager in Kuwait has already completed the introductory physics and calculus classes in 18 days.

Curriki, however, isn't meant to replace going to school but to supplement it and offer courses that may not be available locally. It aims to give teachers classroom-tested content materials and assessments that are livelier and more current and multimedia-based than printed textbooks. Ultimately, it could take the Web 2.0 revolution to school, closing that yawning gap between how kids learn at school and how they do everything else. Educators around the country and overseas are already discussing ways to certify Curriki's online course work for credit.

Some states are creating their own on-line courses. "In the 21st century, the ability to be a lifelong learner will, for many people, be dependent on their ability to access and benefit from online learning," says Michael Flanagan, Michigan's superintendent of public instruction, which is why Michigan's new high school graduation requirements, which roll out next year, include completing at least one course online.