WASHINGTON — Loudoun County is the only school district in the D.C. area that does not offer universal full-day kindergarten, and the superintendent wants to change that.

Superintendent Eric Williams wants half of all Loudoun County students to be offered full-day kindergarten within four years, The Washington Post reports.

Right now, more than two-thirds of Loudoun County 5-year-olds attend half-day kindergarten. The full-day program is offered only to students from low-income families, English language learners or children in special education.

Several factors may explain why full-day kindergarten hasn’t been implemented universally in Loudoun County already, according to the The Post:

• Research is unclear on whether average students benefit.
• The school system has been dealing with a population explosion — more than doubling in size in 15 years, and costs to expand the program would be substantial.
• Just building the classrooms necessarily to implement Williams’ planned expansion could cost $36 million over four years.

Already this school year, full-day kindergarten has nearly tripled in size, just to cover all of Loudoun County’s children with special needs.