FAIRFAX COUNTY tweaked the admission policy to Thomas Jefferson High School for Science and Technology in the hopes that it would increase diversity at the elite magnet school. Not only did the changes not have the desired effect, but something equally troubling may have occurred: The wrong students may be getting accepted at the expense of students better suited to the school’s rigor and mission. Fairfax school officials are right to revisit this issue.

Concern about the admission policies has surfaced in light of revelations that one-third of the freshman class at Thomas Jefferson are at risk and have been recommended for remediation in math and/or science. It’s an unusually high number; in past years, it has been in the 8 percent range. Accordingly, some teachers at the school sent a letter last month to Fairfax school officials, faulting the school’s selection process. “Highly random, subjective, and devoid of measures that distinguish students with high aptitude” in science, technology, engineering and mathematics (STEM) is how Jefferson physics teacher John Dell characterized the selection process in a recent commentary for The Post.

School officials told us they too are worried about the unusual number of students needing remediation help. Not only does such a situation detract from the school’s ability to nurture and develop advanced STEM skills of the nation’s next generation of problem-solvers, but it also negatively impacts the students who, instead of being leaders at their base schools, find themselves out of their depth struggling. Fairfax made changes to Jefferson’s admission policies in 2004 and again in 2009, so one question that needs to be addressed is, why are the problems surfacing this year. Is it an anomaly that so many current students are at risk? Or are there, as critics contend, problems with how students are selected and, even more fundamentally, with how math is being taught in middle school?

Jane Strauss, chairman of the Fairfax County School Board, told us the board will take up the issue in July and will start with a full airing of all the concerns. In addition to examining whether the admission test for Jefferson is too easy and whether teacher recommendations should be given more weight, it’s important that the board not lose sight of the goal — yet to be realized — to have a student body at its most prominent school that more closely reflects Fairfax’s entire population. That’s a challenge not only to TJ’s admission process but to Fairfax education from the youngest on up: ensuring that every child with potential has a chance to thrive.