Former DC Public Schools Chancellor Michelle Rhee says in a new documentary that she is proud of the reform efforts she initiated in 2007, measures that have been heavily criticized since before she left the District in fall 2010.

In dozens of D.C. classrooms, investigations into allegations of cheating on the city's standardized tests revealed that answers were changed on the tests after the students turned them in. Improvement in students' test scores are a critical component of the federal No Child Left Behind law, as well as the Impact evaluation tool used for DCPS teachers.

Similar incidents -- in which teachers were discovered changing students' answers out of fear that poor scores would cost them their jobs -- have been uncovered in cities across the country.

But Rhee tells

PBS' John Merrow in the new "Frontline" documentary, "The Education of Michelle Rhee," that while cheating was discovered at some schools, dozens of others "saw very steady gains over the course of the years that we were there, or even saw some dramatic gains that were maintained."

Rhee would like to have stayed with the school system for another four years, telling Merrow, "I lost the job that I loved." She left after Mayor Vincent Gray beat out then-Mayor Adrian Fenty's re-election bid.

During her two controversial years overseeing DCPS, she established the Impact teacher evaluations, which combine students' performance on the standardized DC Comprehensive Assessment System tests and a series of classroom observations to rate teachers. Poor ratings have led to hundreds of teachers being fired, while teachers who perform well receive cash bonuses.

And Rhee's decision to close 23 schools had parents outraged.

"The schools shouldn't have been closed," said Shavan Collier, the mother of four DCPS students. "They should have, you know, put money into bettering the schools instead of closing them."

Current Chancellor Kaya Henderson, who was deputy chancellor under Rhee, has proposed closing 20 schools next year, with a final list due in mid-January.

Henderson's office declined to comment Thursday, and Rhee could not be reached at her nonprofit, StudentsFirst.

"The real thing that Michelle Rhee did was she got us all focusing on the right issues in D.C. -- you know, looking at student performance, looking at teaching, looking at the quality of schools, looking at leadership in the schools," said David Pickens, executive director of the nonprofit DC School Reform Now.

But for all the publicity, some parents and teachers have questioned whether Rhee accomplished anything.

"The success in terms of student achievement and the achievement gap actually expanded instead of retracting [under Rhee]," said Nathan Saunders, president of the Washington Teachers' Union.

The test scores that improved would have improved naturally, he added.

According to a report released last month by the nonprofit DC Action for Children, third-grade students in DCPS have not shown any improvement in math or reading since Rhee's reforms began. Third-grade proficiency is considered a key indicator of whether a student will graduate from high school.

DCPS has begun whittling away at Impact, considering reductions in how

much weight test scores should have in evaluating teachers.

But that is to be expected, Pickens said. "I've been in education for 20 years at some level, and I've never seen a new initiative launched in its perfect state. You kind of get the best that you can get at the time, and you tweak and you augment and you continue to make it better."