For those of you who give the TRAILS assessment, can I open a session for all of the ninth grade and leave it open until I have met with all of the classes?  Or do I need to create a separate session for each class of 25 students or so that take it?  I want to create one large session, so that if I decide to retest them again as Juniors, I can retest them using the same id numbers even though they will be mixed up into different classes.