This is the best educational Web site I have ever seen. They have compiled over 300 animated explanations of science, math, grammar, and other topics. The cartoon characters are cute, they're witty without being rude, the information is accurate, and kids love to watch it.
This is another subscription service, but one that we think is well worth it. You can watch two movies a day for free, but our kids like to settle in and watch them in batches. Unlimited access for a year costs about $80. My highest recommendation is this: When it's time to renew, I never think twice about it. I can 't say the same for other subscription services, such as Britannica.com at $60 a year.