I have responded to this concern repeatedly, and I have taught (both homeschooled and as a teacher) many children from elementary through high school. So, I feel very confident, now that I have 20 years experience under my belt, and I like to reassure other parents as well. You are right that there may be some gaps in knowledge in the elementary years. But, that’s ok. The only reason your child needs to KNOW all that stuff is to perform well on standardized tests. In the long run, the student does ask about almost everything. They also see their own gaps in knowledge as they get older. And when they have a sincere desire to fill those gaps (usually around 12-14, but sometimes as late as 16), they learn very quickly. I know a homeschool boy who crammed 2 years of high school math into 6 months, because he decided he wanted to attend a college that required he be at Calculus level math for entry. He studied like crazy, but he did it on his own. It was grueling, but he wanted to do it. No one made him. And he succeeded. He scored well on the math entrance exam and was accepted to a prestigious college. There is nothing wrong with someone learning photosynthesis at 15 instead of in the 3rd grade. There is nothing wrong with someone learning the state capitols at 12 instead of in 2nd grade. Unless, of course, you want to plug them back into the system at any given point. In that case, then yes you probably need to practice a different method of educating your kids than unschooling. But if you’re committed for the long term to homeschooling, then truly natural, holistic learning can and will work in the long term.