You've most likely seen flip books before. You may have even made a little hand-drawn thumb flip book of your own. A couple years ago, Mark Rosen and Wendy Marvel created FlipBooKit, these cool kits that assemble into a looping mechanical flipbook box. They come with a default set of animated cards with Eadweard Muybridge's galloping horse (I do not envy that man learning to spell his name as a kid), but you can also make your own animation, which I'll show in an upcoming tutorial.
There are instructions in the box, but this instructable and video are here so you can get a few additional tips and tricks. And in the video you can find some advice for adults who are helping kids assemble a FlipBooKit, as that is a whole different animal than an adult assembling it on their own.