First, there's a lot of useful material in the student orientation section you should check out:
One of our primary goals here is not only to make you comfortable communicating using Gmail but also to increase the response time to parent and student inquiries. That has a significant impact on student outcomes.
Gmail doesn't use folders, they use labels. The advantage? You can tag something with multiple labels but keep emails in only one folder.
Create rules to automatically categorize, sort or ignore certain emails.
Built into Gmail is their chat feature. It's evolving rapidly. It used to be called Google Chat, now it's Hangouts and their conference software, Meet, has spun off of it, too. Hangouts can also be accessed as a standalone website or from within Gmail.