My 9 year old has to do reflex math (fact memorization); she wants to get to 100% by the end of the school year. I created a spreadsheet, and started entering her data. I added a linear regression line & explained how it worked. She was immediately suspicious, and began questioning how all the lines worked, and why it’d take so long, etc. I ended up teaching her the intuition for linear regressions, functions, etc. Very enjoyable for both of us.