The context is that I'm an engineer and she wanted to know what I learned in engineering school, so I said calculus. (In my case, I only made it to pre-calc in highschool.) I swear I'm not the type of parent to try and push this stuff on her. I said it's about understanding how things change and then I tried to illustrate it. I'm open to suggestions on how I could answer her better.
Thanks for posting this kind of stuff. I love the day-in-a-life content.
As for calculus, I'm not sure there's more a 5 yo could grasp! But if there is, you could show how a bunch of straight lines arranged just so make a very smooth curve. Reminds me of my time spent playing Line Rider way back when. It's also handy if ever you need to round a corner with some scissors!