How to organize your students' content
Classes in SyncSketch are called Projects. It is recommended to create a Project for each class e.g "Animation Winter 2018". Projects contain reviews which are equivalent to a class assignment, into which the students can upload their work.
To create a new class you can navigate to the Classes tab in the Workspace Settings and click the Add Class button.
For more information on creating projects you can also head over to the following article: Adding and Deleting Projects.
Further Exploration
Having created a Project, your next step will be to create your first Review for a class assignment.