Livebrush is a site I think your kids could not only have fun exploring, but also learn from. In simplest terms, it's a program that allows you to draw. It isn't difficult to create something attractive even when you are as artistically challenged as the Book Chook. While you're creating, you're also solving problems, hypothesizing, exercising your imagination muscle, and learning the intricacies of digital manipulation.
Livebrush is a drawing application. It employs an easy-to-use brush tool that reacts to your gesture. By combining simple motion controls with brush styles, Livebrush offers a fun and unique way to create graphics.
Use graphics you create in Livebrush within your existing projects. Create entire compositions in Livebrush alone. Share styles and see how others combine your brush with their ideas. Give it a try, or learn more.
It's a free download. You can watch a video demo about it at the site, and check out a little more on the about page. Basically for me, it was pretty much about experimenting and changing settings to see what I could do. Experimenting like this - I wonder what would happen if I changed the velocity? - and trying to find patterns, trying to compare, generalize, modify and rearrange means my brain is involved in higher order thinking skills.
And it's fun too!