introducing R to high school students

I participate peripherally on a listserve for middle- and high-school
science teachers. Sometimes questions about graphing or data analysis
come up. I never miss an opportunity to advocate for R. However, the
teachers are often skeptical that their students would be able to
issue commands or write a little code; they think it would be too
difficult. Perhaps this stems from the Microsoft- and
spreadsheet-centered, pointy-clicky culture prevalent in most US
public schools. Then again, I have little experience teaching this age
group, besides my own kids and my Science Olympiad team, so I respect
their concerns and expertise.

I don't know yet what software they generally use, but I suspect MS
Excel and SPSS.

Now I have to put my money where my mouth is. I've offered to visit a
high school and introduce R to some fairly advanced students
participating in a longitudinal 3-year science research class.

I anticipate keeping things very simple:
--objects and the fact that there is stuff inside them. str(), head(), tail()
--how to get data into R
--dataframes, as I imagine they will mostly be using single,
"rectangular" datasets
--a lot of graphics (I can't imagine that  plot(force, acceleration)
is beyond a high-schooler's capability.)
--simple descriptive statistics
--maybe t-tests, chi-square tests, and simple linear regression.

Alas, probably more than we would have time to cover.