If you haven't yet connected crochet and knitting to your math-ish homeschool lessons, give this article from Wonderful Engineering a read. I made this "unball" filled with negative curves, knowing only a single crochet stitch. Little skills open up big concepts when it comes to playing with string!
Comment below: What age do you think is the best time to take up crochet? How come?
Are textile crafts a part of your heritage? Who taught you?