Is there a minimal threshold for family income where the low family income in aggregate will begin to interfere in the learning process?

“Kids do not leave poverty at the school gate, but wow am I impressed with schools that truly make a difference to these kids. My mantra relates to every kid deserves at least a year’s growth for a year’s input – and some kids (like School B) need more than a year. And my work is based on evaluating these impacts and there are some stunning schools – does School B know how many kids get greater than a year’s impact – and more important can they meaningfully converse on what a year’s growth looks like in their school – if they do not then it is too random for me” (John Hattie, personal communication, September 22, 2016).