A small child's intellectual capabilities begin to develop as soon it is born and by age 4 they have developed most of the basic capabilities they would require for their adulthood. The brain never stops growing though and keeps on assimilating and organizing the knowledge it had acquired.
The question is would a child really benefit from spending time coloring in outlines of pictures created by someone else? You can find the answer by thinking of the benefits kids get from colouring in. When a child visits an online coloring page and begins to indulge in the activities there, they learn to appreciate the value of taking their time to ensure that they do a good job. They also teach them to take pride in what they do and know they did their best.
The theme: Coloring books generally have a theme of sorts. It might be that they are based on a Disney movie, or it is about animals, or vehicles, or something else. When selecting books for your children, remember that they will want to express their creativity, and will have a lot of fun with any coloring book, but will be more interested in a coloring booklet with a theme that appeals to them. Choose a color book that features their favorite characters, or the item of interest in their life. For example, if your little boy just loves trains, get a Thomas the Train coloring book. If your little girl is as girly as they come, look for the Disney Princess coloring book, or possibly Strawberry Shortcake.
It is important to understand that color by number books and e-books are designed for kids, who have particular difficulties with learning and also attentiveness. Lots of adults have appreciated the advantages that these coloring pages offer. The key advantage of color by number books is that they actually turn the whole process of learning in to an exciting gameplay. Therefore your child will study maths basics whilst having a great time with various images.
Occasionally, you'll find official cartoon or TV character sites (such as PBS programs) will make available coloring pages for free to their fans. And there are many other sites that distribute coloring pages of those copyrighted characters. Sounds like dangerous legal ground ...but, surprisingly, I've never heard of any of these sites being prosecuted for copyright infringement. So they'll probably continue to make them available.
When I was a kid I just loved Superheroes and cartoons. It's no surprise then that my favourite thing to do was to watch Spiderman Cartoons! I would plan my whole day around them to make sure I didn't miss them, often running home from school just to see them, even if I knew they were repeats.