Different users, same machine, resume behavior

I have somewhat of a unique situation where the students in our schools share computers in a lab with the same username and password and cycle in and out all day.  We are currently not using an LMS so this story is used either HTML or HTML5.

I'm passing a session variable from a .aspx page with the students' username which is stored in an internally hosted database where their final grade will also be stored.

I need a way for the activity to resume based on the username I passed to the story as opposed to the flash object located on the local machine since the cookie will never change for different users.

Any ideas would be greatly appreciated.