Loomio is a hosted cloud platform designed to "make it easy for anyone, anywhere, to participate in decisions that affect their lives." It includes a variety of decision-making and deliberation tools with email integration.
It is free/libre, open-source software, but it is not easily self-hosted. The hosted service is available on a freemium pricing structure.
Loomio can be used by students to coordinate group projects. Paid Loomio groups can have subgroups that students could use for breakout groups.
A class could use a Loomio groups to make decisions such as identifying meeting times, changing class policies, and more.