e.g. Question: "Every particle of water is like every other particle of water." Use Dalton's ideas and your knowledge of water to explain why.
Student's answer: Because all water atoms are the same but they have to be only water and nothing else. So carbon and water atoms are not the same.
I could give more examples, but they're all equally depressing. I'm sitting here with my head in my hands wondering if anything I've said in the past year stuck.
And chemistry is supposed to be her best subject of the sciences.