The first time I heard the phrase 3rd person teaching I wasn't sure what the presenter was talking about. It was in a Covey Principle Centered Leadership class and I'm pretty sure I was the only person in the class who didn't know what it meant. Or maybe some of the others weren't brave enough to admit they didn't know and they breathed a soft sigh after I asked and the instructor answered. The simple idea is that someone teaches you, then you take what you've learned and teach someone else. When you do this your depth of knowledge increases. So why not try this with agile?