According to a study in Tennessee, children from poor backgrounds offered a pre-school program (for 4-year olds) did worse in several important categories by Grade 6.
This is not supposed to be true. It is counter to other studies which generally showed that children do better — they graduate high school and have fewer disciplinary issues– if they have an extra year of school at about age 4. For as long as I can remember, that has been the accepted wisdom on pre-school. But this study flatly contradicts those assumptions.
If it survives further analysis and assessment, it will have to be taken into account regardless of the politics of government-funding for pre-school.