Well my daughter, who is a bit of a tomboy, grasped the principles of the ADF and VOR in minutes using FS9. After a few real world jumpseat trips she was hooked! Just treat FS9 as the bare bones, a few decent add-ons, say a GA aircraft with realistic cockpit and flight dynamics, clouds, terrain model and some VFR scenery are enough. Just let kids get beyond the 'let's crash it' phase and if they're interested they'll start learning.