evidence: Earlier this year, the National Academies of Sciences, Engineering, and Medicine published a 415-page report on English learners. The report cited 12 studies — dating back to 2004 — that found this gap between Spanish-speaking English learners and other groups. [...] But Nelson Flores, a professor at the University of Pennsylvania's Graduate School of Education, grew up in an area of Philadelphia with a lot of Spanish speakers, too, and he says that's not always the case. In fact, he doesn't think the Spanish-language achievement gap has much to do with language at all. [...] It's no surprise that researchers studying this trend in the past have used income-based controls — such as whether a child qualifies for free or reduced lunch. Those researchers have still found Spanish speakers lagging.