But even if none of those things is true, I keep hearing about classroom size as one of the key determinants of educational outcomes. Well, what's the classroom size for a homeschool? It's however many kids you have. Let's use the standard family size, 2.3 kids. The average school classroom size is around 20 in the US. Well, how much does 2.3 vs. 20 make up for the parent not being a great educator? And what if the person with 20 isn't a great educator either?