Numberphile is legitimately one of the best educational channels on YouTube—Brady Haran has been doing this since 2011 and it shows. The videos are thoughtful, well-researched, and genuinely entertaining if you have even a spark of mathematical curiosity.

That said, it's still YouTube, and that matters. Even though Numberphile itself is pristine content, you're still building the habit of turning to YouTube for entertainment and education. The autoplay feature doesn't care that your kid just watched something enriching—it'll happily serve up whatever keeps them watching.

The content quality is exceptional, but it's not for every kid. If your child lights up at patterns and puzzles, this could be gold. If they're already struggling with math anxiety, starting here might be too much too soon. The pedagogical appropriateness varies wildly by video, as Common Sense Education notes.

Bottom line: This is as good as educational YouTube gets, but that's different from saying it should be your go-to screen time. Use it intentionally—watch together, discuss, and don't let it become background noise or an algorithmic gateway drug.