Unblock Me

It is a little late to be telling you this, but you may have heard anyway that Stanford is offering a class on artificial intelligence free on the web to tens of thousands, including me. It is being conducted in a very rigorous, detailed way. One thing I find interesting about it is that it addresses sliding block problems, which date back to the plastic things you fooled around with as a child, trying to get the blocks to go from 1 to 15 in order. Unblock Me will make you smarter, forcing you to start with your end in mind, in a highly visual way. Available on iDevices; I don't know about elsewhere. A lot of challenge for free.