So, it's good when an academic, James Heckman, documents all of this and proposes some solutions - early intervention
Schools, Skills and Synapses (pdf, 95pp) by James Heckman:
This paper discusses (a) the role of cognitive and noncognitive ability in shaping adult outcomes, (b) the early emergence of differentials in abilities between children of advantaged families and children of disadvantaged families, (c) the role of families in creating these abilities, (d) adverse trends in American families, and (e) the effectiveness of early interventions in offsetting these trends. Practical issues in the design and implementation of early childhood programs are discussed.If you don't have time to read the whole thing (I haven't read it yet) then read the 15 point summary in the introduction.
The distinction is made between cognitive abilities, which are measured in tests, and "socioemotional skills, physical and mental health, perseverance, attention, motivation, and self confidence" which provide the necessary and essential foundation for building those cognitive skills and which are often missing in children from disadvantaged backgrounds. This in turn is used to critique the NCLB (No Child Left Behind) policy which demands that teachers achieve improvement in cognitive results without providing the means to improve the socioemotional (or non cognitive) skills of these students
This is the reality for teachers and students in Disadvantaged schools, the day to day sad, funny, wretched, frustrating, stressful, exhilarating lived reality that does not need belated academic confirmation, but nevertheless, will welcome it