Subject separation
Separating subjects is totally a made-up construct. I have homeschooled seven children. The oldest ones started their learning like public school, in that I tried to teach separate subjects, the way I had been taught. About five years in, I switched to Charlotte Mason and then to TJED, away from workbooks and textbooks. Without textbooks to delineate "this is math, that is science", we learned from media that discussed everything as it relates to each other: DK Eyewitness books, biology card games, videos that applied statistics to populations and demographics, the history of everything: pop culture, fossils, animals, genetics, music, proportions in art... By the time my younger children, born while I was homeschooling, got to assembling portfolios of their work, they didn't see any boundaries between history, science, writing. They recognized the mechanics of doing math as a separate endeavor, but then they applied math concepts to real things. And they discussed them like they had swallowed thesauruses, because that's how I talk.