The newly-revised procedure never specifically instructed the students to add the ethylenediamine to the reaction. And I didn't catch that fact as I skimmed over it.
Net result: My students spent nearly two hours in the lab today turning cobalt (II) chloride into...cobalt (II) chloride.
What a colossal waste of time.
I've never seen a full episode of "The Big Bang Theory" or "Breaking Bad", but I'll happily watch a college football game involving teams I don't particularly know or like.