My two kids (12 and 15) are newly stuck at home, and I'm looking at it as a great opportunity to teach them more computer science than they might learn at school. Both have mastered what Scratch has to offer them, and I'm looking for something more in-depth than what and Khan Academy have to offer - especially if we might actually be stuck home for a long. In particular, I want them to move beyond the block-oriented programming pedagogy used by and Scratch.

What resources can you recommend that are in-depth and age-appropriate? I'd be open to college-level textbook recommendations.