Need to Brush Up? 4 Online Education Sites—and an App

School starts in about two weeks and if your kids spent their summer outside, they may need brushing up on some skills. Fortunately, help with reading, math and more is as near as your laptop or iPad, and here are five places to check for the right sites and apps:

Writing on Parenting.com, Melissa Taylor recommends FunBrain and Whyville, two sites offering fun games that will help sharpen math, reading and other skills. The sites are designed for younger students, but can hold kids' attention with the interactive games.

National Geographic Kids can make studying geography a whole lot more fun—why just read about the Serengeti when you can see it? Videos, articles and more will keep kids busy learning for hours.

The Khan Academy is a school on your computer, and by school we mean K-12 and college. There are hundreds of quality instructional videos on all subjects, at all grade levels—but the classes are, well, classes (maybe the best prep for back to school?).

And naturally, there's an app for that: HuffPo's Brad Spirrison said middle schoolers can improve algebra and math skills with iSolveit, a free app in his article on the Best Back to School Apps for Middle Schoolers.

Do you have a favorite site or app for your kids? How do you get your kids ready to go back to school? Share your answers in the comments below.