Here is an even easier, quicker motor to build. It is more for older kids though, and safety goggles are absolutely necessary! This little sucker takes less than a minute to assemble and gets up to thousands of RPM’s in a hurry. If it comes apart (and it easily can) at that speed it might send that woodscrew flying, hence the goggles.
The critical part is the little neodymium magnet.
You usually have to give it a spin to get it started.
Look at this link for instructions, then search the internet for some more pictures, videos, or instructions. http://www.evilmadscientist.com/2006/how-to-make-the-simplest-electric-motor/ Search for “world’s simplest electric motor”