2600 and its back catalog,
Hacker's Manifesto,
Anarchist's Cookbook,
The old philosophers (Marx, Nietzsche, etc.),
The Federalist Papers,
History Books,
The C Programming Language by K&R,
Absolute FreeBSD.
Really, a blank slate and a promise to help them with whatever they want to learn.
Anarchist's Cookbook is a horrible suggestion, unless you want your 14 year old maimed or permanently jailed in a flawed pipe bomb building exercise. It is filled with dangerous and incorrect information.
Really, a blank slate and a promise to help them with whatever they want to learn.