One of your sworn duties as a parent, of course, is to know everything, or at least make a good show of it. Sometimes the job is easy, such as explaining how Santa delivers eight billion presents in a single night, but what do you do when your child offers up a real challenge—such homework headaches as long division, say, or parsing a sentence? If you're like most adults, such basic nuggets of know-how have long since been buried under years of ER reruns and the reckless use of calculators.

Thanks to the Internet, you're not alone anymore. There are scads of Web sites devoted to helping children and their befuddled parents brush up on the three R's (and history, science and social studies to boot). Some of these sites are specifically devoted to homework-stressed kids and offer links to hundreds of Web sites on nearly any imaginable subject. Others are ultra-specific, such as a site where your kids can relive the Cuban Missile Crisis via video and audio clips. These are the sites we visit when we're in a homework bind.

Please keep in mind that, due to the fast-evolving nature of the Internet, Web sites are subject to change. Originally published August 1999. Updated September 2000.