It does work eventually. If you tell kids enough times to move their arms, and prevent them from actually drowning, they figure it out by trial and error in the end. But that's not teaching.

It's a tragic fact that most people not only can't teach, they lack the introspective abilities necessary to understand that they can't teach. They just can't comprehend that something they find easy is actually hard, or that something they perceive as atomic has steps. Thus they blame the students for their poor teaching skills.

Were you moving both your arms and your legs? At the same time? If not, perhaps it was a reasonable starting instruction. From there perhaps they were planning to proceed to "No, move your legs up and down... yes, like that, but don't forget to keep moving your arms!"

I don't know... that seems like a pretty good explanation to me. Caps lock makes anything better.