It depends how you look at it. If you're looking for moments of one-on-one instruction or school work, it takes none of that. If you're looking for hours of mindful living with the hope and expectation of learning, then it will take all your time.
If you come to see and understand unschooling, then the question about how much time it takes will seem like asking "How many hours a day are you alive?"
Page 6 of The Big Book of Unschooling, which links to
SandraDodd.com/howto
photo by Sandra Dodd
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