There are many ways to solve Rubik's Cube. Here are some of the simplest solutions. Not the quickest, but the easiest to learn.
3x3x3 beginners method
Beginner's giude (pdf): A really simple solution, with only a few algorithms to learn, with really clear child-friendly notation. The real advantage of learning this method is that it upgrades to speed methods very easily. (It is same as our Beginner's giude (pdf), almost)
3x3 Gear cube