Ask HN: My niece wants to learn about "computing". Where do I start?

My niece asked if I could teach her about computing. She's about 8, but she's vehemently opposed to so-called "fluffy stuff" - her words. I was thinking I'd just bust out the Wizard book and work on it with her and her brother, but perhaps it may be too abstract?

She seems more interested in thinking about computing than programming games, etc; so any recommendations on where to start?