Star Wars: Jedi Academy
Well, Star Wars: Jedi Academy doesn't come in a sweet mechanical vault or reveal ancient secrets of the Jedi discipline like The Jedi Path, but I bet it will be an easier purchase to share with your kids. I mean that in the sense of both reading the book together and, more importantly, allowing Jr. to use, handle, or even look at it from afar without your direct supervision.
Now pretty much a household name in Star Wars children's literature, author/illustrator Jeffrey Brown uses Jedi Academy to transport his readers to a middle school. A middle school in a galaxy far, far away. There a young boy named Roan Novachez uses comics, journal entries, letters, doodles, and newspaper clippings to trace a tale that all began with a mysterious invitation to attend a place called Jedi Academy.
Roan's dream was to go to Pilot School like his older brother, father, and grandfather. Inexplicably, he didn't get in. Jedi Academy though--a school he didn't even apply to--wants him. His story unfolds over the course of his first year there. He writes of his Master Yoda, the keys to fencing with a lightsaber, and how to lift boulders with the Force. Seems like there should be some sort of bully with Dark Side tendencies Roan has to out-grasshopper over the course of the year and face off against in the plot's climax too, but maybe Brown is saving that for Star Wars: Jedi Academy 's second installation, Return of the Padawan.