I'd recommned the No bullshit guide to math and physics (http://noBSgui.de) which is a book that introduce the reader to two poerful modelling tools: mechanics and calculus.

But then again, I might be biased since I'm the author ;)

Another thing that would be useful as an introduction to computing is this SymPy tutorial that covers many manth topics that highschoolers are familiar with: http://minireference.com/static/sympy_tutorial.pdf