The vast numbers of benefits to children practicing on coloring pages simply can not be overstated from a psychological point of view. It's important to start children on easy images so that they can experience a sense of achievement. As their coloring skill improves, they can be given more complex patterns and images to color. Giving children books and pages to color is a highly effective way to help them become better artists and writers, to enable them to concentrate better, to reduce the likelihood that they will suffer from mental problems, and to teach them important life lessons and values. Children who begin coloring at a young age will enjoy the benefits it can bestow for years to come.
As already mentioned free coloring pages are a great way to teach your child all sorts of things, numbers for example. There are different ways this can be done, one way would be to simply have the number somewhere on the page, such as the number 10, and then somewhere else on the page would be an object or animal cleverly twisted into that number. There could also simply be 10 of something on the page, you can get your child to color the page in and then count out how many apples for example there are, which will obviously correspond to the number on the page.