In D.C. schools, she found another culture entirely. IMPACT spans an exacting set of nine performance criteria covering virtually every aspect of pedagogy, including clear presentation, behavior management and skill at asking questions. Teachers are graded on a 1-to-4 scale (ineffective, minimally effective, effective and highly effective).

Wysocki’s 2009-10 evaluation was peppered with twos.

“Your instruction needs to be clear and differentiated to meet your students’ diverse needs,” Sean Precious, then MacFarland’s principal, wrote. “Instructional time should be maximized and student misbehavior should be minimized. Please review your IMPACT binder.”

For the year, classroom observers rated her just short of effective. Her value-added score was low. That left her overall rating in her rookie year as “minimally effective.” If it happened again, she would face dismissal.

MacFarland, on Iowa Avenue NW in the Petworth neighborhood, also was struggling. Four out of five students at the school come from families poor enough to qualify for meal subsidies. Fewer than three in 10 scored proficient on the 2010 city reading test.

But Wysocki got better in 2010-11, improving her ability to tailor lessons and gaining a reputation for her skill at managing multiple groups of children in various activity centers. She drew praise from Assistant Principal Branch for “new and innovative ways” of engaging parents, “dedicating a truly exceptional amount of time towards partnering with them,” through invitations to class events and walking home students who live nearby.

“One of the best teachers I’ve ever come in contact with,” said Bryan Dorsey, head of the MacFarland PTA in 2010-11, who had a daughter in Wysocki’s class. “Every time I saw her, she was attentive to the children, went over their schoolwork, she took time with them and made sure.”

The twos from her first year’s classroom observations were replaced by threes and fours.

But Wysocki was worried. Some students who had scored advanced in fourth grade, she said, could barely read.

“I’m getting a little nervous about testing,” she wrote in an e-mail to Branch and new Principal Andre Samuels in February 2011.

Complicated system

The calculus that ended Wysocki’s career in D.C. schools started as a way of measuring the value of strawberries turned into jam. Value-added began in agriculture, where it was employed to establish the worth of farm products as they changed form. Statistician William Sanders pioneered its conversion to classroom use, starting in Tennessee in the early 1990s.

It’s complicated enough that D.C. schools hired Mathematica Policy Research of Princeton, N.J., to crunch the numbers for each of the 471 teachers in the District from fourth through eighth grades whose students took reading and math tests.

In Wysocki’s case, the firm took the fourth-grade scores of each student in her class and searched for all students in the city with the same numbers. Then, after the students took the spring 2011 tests, Mathematica averaged the scores, weighted for the actual amount of time each student spent in her class and taking into account demographic variables.