If you consider the students a school classroom you will note two types of kids. The ones who aren't learning and the ones who are. The ones who are learning are either doing it because they are truly interested and self-motivated (in which case they would be learning regardless of being in school) or because they have been taught at home. The most successful students are the ones who have been taught at home from an early age, where formal school is usually the supplement. In this case, many children are homeschooled; just most of them attend public school as well. This was the case in my own upbringing.
To some extent or another, ALL children are homeschooled--all children learn the basics of life, society, what's expected of them, and basics about the world through their family environment. Learning takes place in the early years of life at all hours of the day, whether or not the "teachers" realize what or whom they are teaching; it's simply a matter of what is being taught. As a result, some children as experts in pop culture. Some children got an a+ in their informal "Mario brothers 101" class. Every child is an expert in SOMETHING, depending on what was presented to them and what values were important in the home they grew up in.
As a homeschooling mother I raise my children in a scholastic environment where they are exposed to books and ideas and witness parents using our education and openly discussing concepts on a daily basis. I know I have fostered my children's interest successfully when I see my four year old teaching herself to read so she can be involved in family reading, when she picks up a workbook and does it on her own, or when my 7-year old puts on a historical audio book every night before bed because he wants to. In this light you see that I really don't have to Teach my children anything, they are fully capable of teaching themselves.
As we seek to educate our children, there are only 2 things we need to teach them: to take an interest in the world around them, and where to find answers to their questions. These are the vital precedents of becoming educated, and once a person obtains these, they can't help but to become educated, whether they are in a classroom, a home with a set curriculum, or on their own without any schooling at all. In this case, you can take a look at our society and see two types of people: those who are interested in the world around them and find answers to their questions (the educated members of society) and those who do not. Unfortunately, the school system has graduated and deemed "educated" far too many students who do not meet this criteria. Perhaps they were once interested in the world around them, but after having their desires and voices stifled by public institutions for 13 years, they simply gave it up. The result is the public school system produces exactly the opposite of what is was intended to do, and we have a society consisting far too greatly of numb robots who have forgotten who they were originally when life began.
Thankfully, we have many parents who are homeschooling their children....even if they do supplement with public school.