Another good point.
Good point Abas-san.
The word "teach" does not mean it has to be in an audio-visual sense. This will start getting to the philosophical sense of teaching.
Just last night, after the technique was succesfully done, my partner asked if he did the technique correctly. So I asked him back if I was faking my attack. He answered that he does not believe so. So I said that he did not need to ask me if it was done correctly or not, he will know it himself.
Most of the aikidoka at the dojo that has been practicing quite a while will know when something is not correct. From partner practice point of view, this can be achieved when there is a truthful uke-nage relationship.
What do I mean by truthful? I don't think I have to explain. I believe you all know what I mean.