DC Public Schools is negotiating with the Washington Teachers' Union to extend students' time in class, according to Schools Chancellor Kaya Henderson.

"We are creating more flexibility within the teachers

union contract so that we can actually implement a longer school day and a longer school year," she said.

DCPS spokeswoman Melissa Salmanowitz said the school system is not ready to release the details of the proposal.

Though Washington Teachers' Union President Nathan Saunders was similarly reluctant to reveal details before the contract is finalized, he said any proposal that lengthens the school day would need to include additional pay and professional development for teachers.

Many public charter schools in the District already offer longer school days.

KIPP DC, for example, touts an extended school day, Saturday school and mandatory summer school, resulting in 40 percent more classroom time for students at

KIPP schools than students in DCPS schools. The organization operates 10 high-performing charter schools in the District, with more than 3,000 students across three campuses in Wards 2, 7 and 8.

KIPP co-founder Mike Feinberg has attributed the organization's strong academic performance largely to the extended days.

KIPP is not an anomaly, said Ward 3 D.C. Councilwoman Mary Cheh. Studies have shown that more instruction time improves academic performance.

Henderson said she has been seeking advice from charters such as KIPP in developing changes to school schedules.

In 2010, Cheh introduced a bill that would have added 30 minutes to the school day, but the bill didn't go anywhere. Now, though, with Henderson onboard, Cheh said she is hopeful the change might happen.

Teachers unions have been known to fight extensions of the school day or year because they say

the changes affect

teachers' family lives and abilities to hold second jobs over summers. Cheh suggested combating this by letting teachers volunteer to work longer hours, offering more pay in return.

"We have to, maybe on a pilot basis -- probably on a pilot basis -- let schools apply for being the schools that will have longer days or possibly Saturday classes or a longer school year," she said. "[We should see] whether an increase in time in school instruction can really help raise scores."