September is the most important month for teachers. It's a decisive moment for them to organize (even though this should have been a previous work), meet their students and face new teaching challenges. This is the perfect opportunity for learning about open resources that could be helpful.
I'm currently teaching Linux/security in exchange of self-defense classes. I really wanted to use a shared document without counting on Google and I decided to use a disroot pad; we are getting along so well with it, it allows basic editing, comments and it's easy to use.
If you are teaching any computer science subject, using gitlab is a really nice resource. I had a teacher at university that used this method and forced us to learn about testing, pull request and git. This is a real-life experience as well as handy, because you can take advantage of the Kanban board as well.
For communicating and organizing, you can use Matrix (chat) and maybe if you feel comfortable enough programming and deploying you can consider using redmine as an students platform.
For creating a public book list that your students can take a look at, I suggest inventaire and incipient, yet easy to use, webapp for making a library.
Of course, using a Linux OS is a must, for that some of the most user friendly are the classics: Mint, Ubuntu... also Elementary if you feel more comfortable in a MacOS-like OS.
I invite you to comment more examples that can be useful! T