You need three graphs to explain how education works in the U.S.
The first graph tells us about the students.
The data comes from the National Longitudinal Study of Youth.
This is our raw material. By far the most important variable affecting the inputs of education is IQ. Simply put, it's far easier to educate a smart kid than it is to educate a dim kid. The sad reality for the low IQ kids is that IQ is a brutal predictor of academic success.
In the U.S. the mean IQ is about 100. We know how to educate the kids with IQs above about 100, at least at the K-12 level. The kids on the left half, not so much.
There are thousands of schools in the U.S., each teaching a little differently. However, the results are almost always the same: the kids on the right succeed and the kids on the left fail. This is because most of the differences aren't instructionally significant. (I'm ignoring for the purposes of this discussion the handful of specialized programs that are capable of improving the educational outcomes of elementary school students because there is little hard data for the upper grades.)
IQ isn't the entire story when it comes to academic outcomes, but it is a major factor. There are lots of other environmental factors that affect academic performance. These factors have a distribution like IQ. So to give an extreme case, the kid with the 95 IQ with the good work ethic and parental support may perform better than the kid with the 105 IQ with behavioral problems and dyslexia.
Now that we know about our student inputs, we have to recognize that kids are not evenly distributed in society. Kids live with their parents, usually in a house that their parents pay for. Typically, parents buy or rent in the best neighborhood they can afford which is largely determined by their socio-economic status.
Graph 2 shows us how children's mean IQ is distributed according to parental SES. The parents with the high SES tend to have the children with the highest mean IQ, while the parents with the lowest SES tend to have children with the lowest mean IQ.
This is why schools located in affluent suburbs perform better than schools in poor areas and perform much better than schools located in the inner city. If an affluent suburban school is pulling most of its students from an area where the parental SES falls within the 7th to 10th decile, you can see how the white kids will have mean IQs in the 110-115 range. Even the black kids in that school district will have higher IQs than the average black kid, though these kids will tend to have lower IQs than the average white student. (This explains the disparity in scores that I highlighted for Radnor Middle School in my last post.)
You should also be able to see why a poor rural school comprised mostly of white kids will tend to have students with a below-average mean IQ. And, this also explains why poor inner city schools comprised mostly of black and Hispanic students is going to be full of students with extremely low mean IQs. At best, these schools will only have about 20% of its students with IQs over 100. And remember what I wrote about us not knowing how to educate kids below IQs of 100.
This is why NCLB cares about the subgroup data for blacks, Hispanics and poor students in affluent suburban schools.
Which brings us to the third and final graph. The third graph is a scatter plot of the academic performance of Pennsylvania's 501 school districts as a function of Parental SES.
As you can see, the results are exactly what you'd predict from the first two graphs. The schools from high parental SES areas with kids having a higher mean IQ tend to perform better, while the schools from low parental SES areas with kids having a lower mean IQ tend to perform worse. (I'm not going to post the graph that plots academic performance vs. instructional spending which shows a very low correlation.)
The schools falling below the regression line are under-performing. The schools falling above the regression line are over-performing. I've highlighted (white arrows) two clusters of schools. The first group of slightly over-performing schools is located at about the $27k point. The second group of slightly under-performing schools is located at about the $67k point. Notice how the academic performance of the over-performing cluster is below the performance of the under-performing cluster. Under NCLB, the under-performing schools would likely to be labeled as success stories, while the over-performing schools would likely be labeled as failures.
I don't mean to imply that schools shouldn't be doing a better job or that there isn't lots of room for improvement. They should be and there is. The point of this post is to highlight the reality that most schools in poor areas aren't doing all that poorly and the affluent suburban schools aren't doing all that well once you consider the hand they've been dealt.
We need to start approaching education with Occam's razor instead of Occam's butterknife if we expect to fix NCLB.