Viewing all available keyboard shortcuts on a Chromebook is easy. 

Press CTRL + ALT + ? to view and search al keyboard shortcuts. 

Here are some of the most useful.

Copy:     CTRL + C

Paste:     CTRL + V

Caps Lock:     SEARCH + ALT

Lock Chromebook:     SEARCH + L

Logout:     SHIFT + CTRL + Q (Twice)

Take screenshot:     ALT +  Show Windows  

Take Partial Screenshot:     Shift + Ctrl + Show windows   

Open apps on the Shelf(Dock/Toolbar)

Hold ALT and press the corresponding number to the shelf. 

If Chrome appears first it would be ALT + 1

If Camera was second it would be ALT + 2

Pin an app to the side of the screen: ALT + [   or ALT + ]