I sat on the floor with my dog and taught him to roll over in a few sessions. Each session was five minutes, and he had it by the end of each one.

The third session was a bit different from the first two because I sat in a chair. I began by making a whirling motion with my hand and saying "roll over". He quickly shuffled a few feet to the right, crashed hard into the wall, and fell over. He looked confusedly at the wall, and then at me - the wall for attacking him, and me for withholding his reward of food.

He had, after all, performed the trick that I had taught him - pointing his head at my crotch and shuffling to the right, not stopping until he flipped 360 degrees.

That I intended for him to be learning to roll over didn't matter - this is reinforcement learning.