SCORM

You could put 'new' students in a group and hide (using activity restrictions) old activities from anyone in that group and hide new activities from anyone not in that group. Then there's no confusion about what they should do. Do you have ways to mark the 'new' students complete? I've got a course where 30 or so students completed the original 5 modules and then we 'replaced' them from a curriculum perspective with 9 or 10 new ones. I placed the original 30 students in a group and placed view restrictions on the original modules (must be in that group). The new modules got view restrictions for anyone not in the group. The activity following these modules required all 5 modules be complete. I modified the restriction to be must complete original 5 OR new series. It takes some time and coordination but can help.