EVEN BEFORE DETAILS are released, critics are circling to attack the school-closing proposal that D.C. Schools Chancellor Kaya Henderson will release Tuesday. The shuttering of a beloved school can be one of the hardest blows to a neighborhood. But some schools have to close, and facts ought to trump emotion or nostalgia in the process.

A report commissioned by the administration of Mayor Vincent C. Gray (D) prepared the ground this year. The report examined the geography of school quality, cataloguing neighborhood by neighborhood what was offered by traditional and charter public schools. The report confirmed that there are too many under-enrolled and low-performing schools. Ms. Henderson has made no secret of her belief that school reform depends upon right-sizing the system.

Even after closing 23 schools under former chancellor Michelle A. Rhee, the District operates many more schools for the number of students served than do surrounding jurisdictions or other urban districts of similar size. D.C. has 123 schools for 47,247 students while Fairfax County has 196 schools for 181,536 students, even though Fairfax covers far more area. Many of the District’s public schools are operating well below capacity, with some enrolling as few as 131 students. Under-enrolled schools do not allow for the best or most efficient use of resources. Schools with larger enrollments have more robust staffing, including librarians and art teachers, and encourage collaboration that is difficult to achieve in small schools.

Ms. Henderson has been careful to brief council members whose wards will be affected, and she reportedly plans a series of meetings in neighborhoods as plans are refined and finalized. It is important that she explain how students will benefit from the consolidations and also what will become of the closed schools. Previous administrations allowed closed schools to lie unused and deteriorate; Mr. Gray’s interest in providing space for quality charter schools is an encouraging sign that better choices will be made with this important real estate.

The D.C. Council has no formal role in school closure decisions, but council members can help build support for the hard choices that need to be made. It will be instructive to see which members rise to that challenge.