[ThrustVectoring]

>How can we get substantive, critical thinking skills earlier into the curriculum so we don't have to just assure students: "trust us, math will get interesting if you can just stick with it through calculus and linear algebra".

Don't teach math to elementary school students. Seriously. The current system mostly just teaches children to hate mathematics. Talk to some random adults if you doubt me - if you like math, you're in a large minority.

There's a good chunk of math that is nearly impossible to grasp until you've developed sufficiently abstract thought, at which point they're pretty obvious. I remember reading something like "sixth graders who enter with zero prior math exposure are merely a year behind fully educated peers at the end of the year". People are extremely good at picking up the mathematical concepts they need that are within their conceptual grasp. Hell, I know someone who wasn't exposed to algebra until they were taking calculus courses for their mechanical engineering major - they had to put in a ton of work and get help from their greek peers, but they passed their courses.