This brilliant talk by Jeremy Keith is licensed for sharing with attribution to Jeremy. It is the best explanation of how HTML5 grew to where it is now and what it means to web design that I’ve ever seen. It’s more about design principles than code.
The transcript and a link to the slides are at Adactio.
I think this material should be included in the InterACT curriculum as an introduction to HTML5 module. With the CC license Jeremy is using that is doable. I hereby volunteer to write the educational jargon like objectives and test questions to wrap it up in so it becomes a usable curriculum module for web educators.