The last time I used it, it was free to download (still is, it appears). Users are able to render 3-d rotatable models of various landmarks via webcams and a couple printed documents. Super cool.
This was my first intro to AR. I heard about it at a conference a few years ago. There was a very smart guy there--I'll have to look up his info and send him an invite to the MOOC. He made an educational AR software that let children create 3-d storybooks. You can find that software here: http://www.zooburst.com/index.php
Forgive me if either of these have already been referenced. :)
The 3D book sounds like a great way to start - thanks for the link.
A skilled teacher knows that technology implementations won't have any impact as long as you try and retrofit them on to outdated teaching methods. Only when combined with the creativity and ingenuity of dedicated teachers can technology have a truly disruptive and transformative effect. "