I'd be interested to see some more examples you come up with if you continue to teach your kids.

I'm re-learning basic trig right now for drawing OpenGL stuff, and I was trying to think what I could have told younger-me on why I should be paying attention in high school for this topic.

When I was in high school, it would have made me more attentive if people said, "Hey, this stuff that finds circle arcs and radius, you can use this in real life if you decide to get into gaming, graphics, .. (and other cool topics that would excite me)."