The only way to do that experiment in a properly controlled environment would be to have the entire student body come from identical socioeconomic backgrounds.

The only way to do that experiment in a properly controlled environment would be to have the entire student body come from identical socioeconomic backgrounds. The lesson of the article I linked is that the more poverty a child experiences, the less effect a teacher will have on their lives. You can choose to ignore that reality all you want, but it doesn't stop it from being true.