1. "Children are motivated most when they discover the meaning behind a subject of their own accord."
Not in my experience. The most motivated children are motivated for a big bag of complex reasons, including desire to please, desire to pass exams, and a general will to solve problems and answer questions. They may also be intrinsically motivated by the meaning behind a subject, but that understanding can also be provoked from outside (eg by a teacher).
2. "Children develop grit through a self-directed curriculum." Again, not in my experience. A rather harsh truth is that children develop some of their grit by not having all their natural inclinations indulged. Numerous are the tales of successful people who excelled because they overcame difficult circumstances.