I can think of a time when I taught a music appreciation class to 7th and 8th graders. I asked them to complete some homework covering Baroque music, specifically learning about the works and life of J.S. Bach. There was a complete revolt by the students. They had no interest in the music or the class. The students refused to complete the assignments and failed the quiz (listening and writing) on purpose. Needless to say I was not pleased with this outcome. I was forced to revisit the chapter taking a new approach to try to gauge some interest in music of the time period.
Generating and testing hypotheses is something that I use regularly in my daily work. Every time I come across a new piece of software or teaching resource I generate a hypothesis on how I think it should work and then test out that theory. In addition, I generate a hypothesis about how the teachers will react and use the new tool. A few times I have been way off on my hypothesis but, luckily, my teachers are open to embracing most of the tools I give them.