Okay, I just found the actual Instructor Guide article and Admin Guide article on Differentiation Tags, and figured it out, I think. These are more helpful than the FAQs. You have to enable it TWICE:
- First, in the Feature Options tab of the root account or subaccount, it needs to be enabled there.
- Then, in the root account or subaccount Settings tab, you have to check the box under the "Features" heading for Differentiation Tags.
I wish it could be turned on or off in a course by course manner by instructors from the course Feature Options tab, but that doesn't seem to be a thing. I just enabled it for our Science and Engineering folks because one person wants to try it out, and I will probably now get a bunch of questions about it since we haven't done an official roll out yet.