This story is about an achievement gap.
No, not the achievement gap — a term used to describe how white and wealthy students perform better on standardized tests than minority and low-income students.
This is an achievement gap you might not know much about, even though researchers have puzzled over it for more than a decade.
This one has to do with language.
We're writing about it now partly because it popped up in a recent Philadelphia study, with new data pointing to its distressing magnitude.
Earlier this year, the Philadelphia Education Research Consortium released a study looking at English learners — or ELs — who entered the district as kindergartners in 2008-09. It tracked their progress through the end of 3rd grade because the city has a goal of ensuring that all students can read on grade level by the beginning of 4th grade.