Every year high school students in Stockholm can apply to a two-week science summer school where they work in research groups at Stockholm University. In 2011 I supervised six students in the Quantum Chemistry group, where we assigned projects on properties of molecules and chemical reactions.
We also demonstrated physics with some fun little experiments, like applying voltage to gherkins to make them glow like streetlights and making icecream with liquid nitrogen. The students also got a chance to visit a particle accelerator and to see the telescope on the roof of the physics building — the largest operating optical telescope in Sweden.
I had been told the students would be motivated — they were giving up two weeks of summer to be there, and places were competitive — still I was impressed by how well the students worked and how quickly they picked up ideas. It was a fun two weeks.