I just realized that earlier in the IC I mentioned Anna having a watch on her. 

Of course, until we get the chance to compare it to a school clock they can't really do much with it. Though Sarcastic could just shoot me down beforehand and say "Yup they're the same time." or some such thing.

EDIT: Though that would only be able to tell us potentially how many hours it's been. Not days, weeks, etc.