...
SU's Blackboard sessions timeout after 4 hours of inactivity. Any work that was done but not saved or submitted prior to the timeout message is unfortunately unrecoverable. This document explains what constitutes inactivity and how to avoid losing your work due to session timeouts. Web Browsers DO NOT register typing as activity. If you're typing an assignment, assessment, or discussion submission for longer than 4 hours, the session may timeout when the submit button is pressed. This means that you may lose your work.
...