Back in my intro to geology class at Mesa Community College, our professor spent a whole lecture on cleavage and fracture, and half the room was trying not to laugh the entire time. I completely agree that overemphasizing cleavage early on can just add unnecessary stress, especially when newcomers are already grappling with the jargon. We had a lab where we had to identify minerals based on cleavage, and I remember my partner whispering jokes every time the TA said 'perfect cleavage'. It totally undermined the lesson because we were more focused on stifling giggles than learning the actual concepts. Starting with luster and hardness, like the original post says, makes so much more sense for building a solid foundation without the distractions.