Harry had been sent to the best primary schools - and when that didn't work out, he was provided with tutors from the endless pool of starving students.

In about eight months or so, I will be one of those (hopefully not starving) students. I'll be moving out to London to live with my aunt and uncle in a rather nice middle-class neighbourhood, while I study and work to prepare for university the following year. They know a lot of the parents around there and suggested that I begin teaching small groups of 8-to-12 year old children for maybe an hour or two regularly, and charge their parents/guardians a reasonable sum per child. I would be teaching them math and science in all likelihood. Apparently word will get around quickly if I'm competent so I might have a substantial number of customers within a few months.

My questions:

Does anybody on LessWrong have any direct experience at this sort of thing, that could share some advice?
What are some good things to teach? I'll probably do the standard bottle rockets and baking soda+vinegar volcanoes, but I'd also want to spice things up and teach them something that they'd be hard-pressed to come across elsewhere (simple rationality techniques come to mind)
What is the best way to teach these things to this age group - or rather, what are some good books or other resources that I can use to teach myself how to teach?
If I were to teach them some basic rationality skills, which ones and how? Obviously I won't be talking about anything fancy like probability theory unless I strike gold and find a kid on the far-right of the bellcurve, but more like low-hanging fruit. I might do something like that radiator puzzle to warn them against password-guessing for example.

(edit: thanks to whoever fixed the font on this)