Remind - Remind, formerly Remind101, is a communication tool that helps teachers reach students and parents where they are. It also allows for translation features to better communicate with all families.
Community Questions for Confluence - Keep questions and answers in one place with an engaging, community-driven Q&A discussion forum, powered by Confluence
Google Classroom - Learning management tool by Google
Question2Answer - A Q&A site helps an online community to share knowledge.
Edmodo - Where Learning Happens
Stack Overflow for Teams - Everything you love about Stack Overflow in a private space.