I just saw a post on Twitter sharing the Google Classroom extension for Chrome to make sharing to your Classroom super easy. It gives you an icon in Google Chrome that, when clicked, lets you select what class you would like to share it with. Super easy!
I had a teacher ask me if there was a way to hide or remove students who are no longer in your class. The answer is maybe. It depends on if they are officially dropped from your class and appearing as red in your roster and gradebook. If not, then no, you cannot remove them until they have been unenrolled from the class. If the student is showing up as red in your gradebook though, you can hide them so you don't have to worry about them. Here is a screenshot to help you do it: