I teach at a middle school, 6 - 8 grades. Mostly 6th grade all day. One of my students could not understand the difference between fur and feather. She was certain that chick had "fur" it did not look like feathers to her. Nothing changed her mind, it was too strange. I hope to have a 4H group started at my school this next school year, so many of my students are too far removed from reality and it is scary. A few years ago I had a student who understood that monkeys were mammals, but did not connect to the fact that humans are mammals too. It was so strange.