This is a comment by eccdogg on this blog post.
There is a pretty nice natural experiment on this with the comparison of Wake Co (Raleigh) and Mecklenburg Co. (Charlotte) schools in NC.
Raleigh for a long time has tried to balance schools by income so that the percentage of free and reduced lunch students was similar across schools.
Charlotte ended busing quite a while ago and instead uses neighborhood schools combined with increased spending on low income schools.
On the face of it it looks like Raleigh’s approach is better because Raleigh’s schools on average do better on statewide test. But that is mainly a composition error. Raleigh is richer and whiter than Charlotte. When you look at minorities and low income students they do BETTER in Charlotte than in Raleigh. Raleigh has fewer failing schools but more failing children, they just hide them amongst better performing students.
Personally I can see how upper class parent involvement could actually be to the determent of lower achieving kids. Upper achievers and lower achievers have different need and need to be taught at a different pace. An upper income parent will advocate for the school setting its strategy based on what is the best for the upper income child. I see this at my daughter’s school (in Raleigh) that is mainly upper income with lower income kids bused in. The school is great with lots of electives and an accelerated pace. This is great for my daughter, but if a kid is struggling with the 3 Rs as many low income kids are they could easily get left behind and all of us middle/upper income parents would not care in the least.