So many social media sites have that age restriction in place so it makes it hard for students to access it as a resource. I have seen teachers create the class account at the elementary level but students are still posting on it. We actually have Twitter blocked by our firewall for all students K-12 (and teachers). I agree with the younger students but could be a used as a valuable way to connect students for global projects or interact with celebrities/ experts on specific topics.
I personally use Twitter all the time and it is the best source of professional development for me. I sometimes just throw out a question I'm thinking about and see the various perspectives or resources that I get sent back in return. It's actually been a great way to gather research articles for a few papers now! You have access to experts who can share their experience and research they've done too.
We don't use Google Classroom even though we are a good school due to using Hapara Teacher Dashboard and ManageBac (in secondary) for submitting assignments.
I also love using Google Docs in language classes. The ability to take editing and revising to the next level is fantastic. Plus there are add-ons for table of contents, referencing etc. One of my favourite features is the 'suggesting' mode instead of commenting where a friend can suggest edits and the owner can choose to accept or deny the suggestions. This really helps the digital revision process come alive.