Things have really started during the week 1 of the MOOC Learn HTML5 from W3C. Here is what to memorize about the basics of HTML5.
HTML5 Differences from HTML4 (December 2014)
Easy content organisation with HTML5
How to know when using DIV, ARTICLE, SECTION, etc. with the HTML5 element flowchart
One of the most popular resources for testing microdata (as well as microformats and RDFa) is the Google page about rich snippets and structured data