Our family takes an “everything is connected” approach to life, but some people prefer to break the world into subjects, perhaps for the sake of being thorough (or because the setting of school requires it of them). It gives you more of a checklist approach to life. Have we done our math today? Have we practiced reading? Have we learned to spell a few words today? Have we spent some time with nature, making sure we are learning about the way of the world? Have we contemplated cultures, people, or methods of governing?
These are all things we encounter daily, and the flow of life naturally takes us there.
Coming from a subject-oriented education myself, I found it surprisingly hard to turn it into words my nine-year-old, unschooled kid could relate to.