Good points. It may be irrelevant in the long term scheme of things if students are all knowledgeable experts on the octopus, but if your ELA lessons are consistently something like "finding the main idea, " then kids are going to want to gouge their own eyes out with a spoon. Think knowledge first, and then what skill will be taught to access even more knowledge from the text, and you'll have a more successful recipe for learning. That's why I poll my class at the start of the year about what they want to learn about. If dinosaurs or space or ocean animals is what's going to motivate them, great, I've found my vehicle for teaching literacy skills. I think the problem many educators face is, What knowledge? Since the question has never been sufficiently answered-- unless it's stated in the skills-based standards, and it's usually not--I just let the kids decide!