Check out Microsoft Teams for Education. It's very nice product similar to Google Classroom.

Maybe even non-educational Teams version would be enough if you just need it for students and teachers to communicate.

https://edudownloads.azureedge.net/msdownloads/MicrosoftTeam...

https://docs.microsoft.com/en-us/microsoftteams/remote-learn...

https://www.microsoft.com/en-ca/education/products/teams

Disclaimer: I developed few features for this in the past.