About 3 years into my training (I'm at 7.5 now), I moved and changed senseis. I was ikkyu at the time and had become (without really knowing it) quite stuck in my thinking. I was pretty stiff too. My new sensei didn't talk much, but he was very clear about the fact that he wanted me to do exactly what he had demonstrated. He had many ways to let me know I wasn't on the right track. Sometimes he would simply use my partner to re-demonstrate the technique. He would then wait and watch me try...if I got it, great, if not he might stand there repeating "no" until I self-corrected. Sometimes he would come over and be my uke...if I did the technique wrong, he wouldn't move or he might even hit me if I left an opening (but only hard enough to make his point...not really painful). I can remember standing there, with him not moving, for what seemed like long periods of time (but they really weren't), I can also remember getting hit over and over (but not hard...just repeatedly). He taught ukemi the same way. There were a couple of times he called me up for ukemi and then told the class not to do ukemi like that.
Now, it would be one thing if he was full of himself or mean spirited...but he actually pushes himself as hard as or harder than his students. He doesn't really toot his own horn or pretend that hes the end all and be all. He is just a stern and insistent kind of fellow. You simply do not get away with not doing the technique right (aka the way he demonstrated it).
Relating this back to the thread...I learned how to learn from this sensei. I learned how to REALLY look at what was being demonstrated. I became MUCH better at being present on the mat...focusing only on what was happening...not on what had happened before. My first sensei had talked about awareness...but it was my second sensei that TAUGHT me awareness. I do not mean to imply that my first sensei was inferior...but I have a tendency to overthink/tense up/lose focus and it took a more hands-on approach to get me past some of that (of course...its still an issue).
This whole in my face, not letting me get away with anything approach was effective but I should note that he doesn't do that with brand new students.... It's a hard road.
To sum-for me learning how to learn Aikido is about awareness...learning how to really see, to really feel...the whole "Zen in motion" thing. I live in a different town and have a different excellent sensei (I feel lucky), but I learned about awareness from that sensei.