Lots of people here are missing the point.
Since the difference predates school it can't be due to bad schools.
It's what's going on at home that matters. Parenting.
do you ever read previous posts?
Providing the mental stimulation for the kid doesn't cost anything.
IOW, the answer is "NO", you do not bother to read or especially think about the contents of prior posts that directly refute your baseless and illogical assertions.
Providing mental stimulation for your kids, including having constant interactive dialogues with them does cost plenty. I explicated numerous plausible factors that are directly or indirectly related to things that cost money, are impacted by being able to spend money to increase one's free time, and stress factors exacerbated by monetary concerns that impinge on the needed time.
If you don't have time to raise a kid you shouldn't be having one in the first place.
Part of parenting is the decision to have one in the first place.
[follow-up comment in subsequent post]
Choosing to have a child in a situation you can't care for it adequately is child abuse in my book.
Wealthy parents don't give any more thought to it and don't put more effort into parenting. It is just fortunate for their kids that the financial circumstances of their parents inherently make it much easier for their parents to provide a superior environment. Take the wealth away from the wealthy and they would still have kids and their same amount of efforts the give now would produce the worse results we see for poor parents. IOW, wealth is the central causal determinant.
Not to mention, kids that know fewer words are not "abused" It is a matter of having fewer advantages relative to others. I realize you "libertarians" don't care about anything but money, but what about relative emotional advantages in terms of having a large extended family to buffer kids against the discord of divorce. It's a 50% chance your kids will suffer through a divorce. Having lots of nearby aunts, uncles, living grandparents can buffer those negative effects by providing a larger context of social stability surrounding the parental instability. So, is it abuse for people to have kids unless they have stable, psychologically and geographically close relations with an extended family network?
The notion that it is abuse to have a child in less than ideal conditions is absurd. Should all people, poor included, be educated on the countless ways in which having multiple children negatively impacts their kids via diluting economic and parenting resources? Yes. And should they be educated very explicitly about birth control, making it a central component of the minimal education requirements and included in standardized testing along with other basic science knowledge? Yes. And should all people be given free access to safe forms of birth control, given the high cost to society of unwanted/unplanned births? Yes. And who are the ones that oppose such sane, ethical, intelligent and efficacious social policies? Conservatives and many self-labeled "libertarians".