What comes to mind for me right now is a general roadmap for k-12. My kids are young, and it would be most helpful to have guidance on where I start now so that by the time they reach high school we’ve laid a groundwork for the more advanced stuff. I’m not afraid of the math, but it won’t be too long before I’m learning alongside my kids and a trusted guide for the concepts I should be focusing on would be worth a great deal to me. Bonus points for tying the learning into age appropriate applications and exercises that are demonstrating and/or solving real world problems.