What you want to teach depends on what you're trying to accomplish. I don't think there's much point in trying to give Aristotle an overview of modern scientific conclusions.

Assuming we want to accelerate technological progress, I'd rather teach him scientific method, decimal notation, evolution, and maybe what Feynman said (iirc) was the most important conclusion-- that matter is made of tiny bits of elements. I don't know what other specific subjects might be a good idea. Bayes? Calculus?

I don't know what would be convincing experiments for atoms.

One more I'd want to teach him that you can learn a lot by doing careful measurement and thinking about the results.

I don't know what Aristotle would come up with, given all that-- he was very smart.