"If we consider that there are two ways to communicate in the world, and Harvard Business School professors are known by two-by-twos -- nonsense, it's the triangle that rocks." (Ted talk "How to build (and rebuild) trust" by Frances Frei)
Context: the speaker is a Harvard Business School professor. She drew triangles while explaining her point.

I'm not exactly sure about what Harvard professors are known by.

 

It's a form of tutoring in which a student is matched with a tutor. So ironically, it's really one-on-one, but they call it two-by-two for various reasons.

 

I don't think so. I think she's referring to two-by-two grids such as this one, which are widely used by business school professors (and not just at Harvard):