i've been lurking for a while but had a thought i hadnt seen on this topic yet.
i think the article and probably the actual study is as much about the teachers as the kids.
When teachers dont expect kids to be able to function at a high level or even grade level, they communicate that in many ways to the kids, the parents, other teachers.
when the kids got high quality, engaging teaching from respectful adults - they responded to that. project based learning that is embedded throughout the curriculum ( ie math, language arts, science social studies) is a hall mark of center based gifted programs. this study suggests kids dont have to be highly gifted to benefit from this type of curriculum.
the fact that low performing schools that had never had a kid identified for the gifted program, then had kids identified as gifted after the curriculum change says more about the teachers at the poor schools than the kids.
high risk kids are just like other kids. When they have good teachers and an exciting curriculum they learn more. and become more focused on their education. gifted kids were always at those schools, they were just never motivated or allowed to shine. noone thought they existed there so they didnt bother looking for them.

many many years ago North Carolina did another study. it probably isnt even ethical now. they created classes of "gifted " students from regular average kids in a few districts. the teachers did not know the kids werent gifted. I dont recall exactly what they told the kids. but as a class, the pseudogifted kids had less discipline problems and higher test scores than they had had previously and also compared to control average kids not told they were gifted. the conclusion of the investigators at the time was raising the expectations of/for kids increased their performance.