Layout Land
If your design focused and like to learn by watching, Jen Simmons has released a series of videos that talk about the design and CSS Grid. These videos feature lots of great examples.
Watch nowWho's the Bos?
Take part in an online course comprised of 25 videos, about 4 hours long. The course is 100% free, as it's content (and Wes's time) was sponsored by Mozilla.
Sign up nowReplace Bootstrap Layouts with CSS Grid
Quick read on the benefits of Grid layout, with usful tips on 12 column grid layout system.
Read the postGrid Layout in DevTools
CSS Grid Layout panel lists all the available CSS Grid containers on the page and includes an overlay to help you visualize the grid itself, including grid line numbers and dimensions.
Learn moreRachel Andrew
Rachel Andrew is a developer, speaker, and author. She is a member of the CSS Working Group and develops resources for learning about CSS Grid Layout.
Learn more...a bit of history
If you're ready for a longer read, here is a post on the story (and a bit of history) of the Grid came to be, brought to you by it's creators.
Learn more