For decades, the system for evaluating K-12 teachers has relied primarily on two things: observation and test scores. But under the Every Student Succeeds Act (ESSA), that could be changing.

The new law will allow districts to use other kinds of evaluation measures including coaching and mentoring, said Anne Udall, executive vice president of program strategy at New Teacher Center (NTC), a nonprofit that aims to improve teacher effectiveness.

"It's allowing districts and states to rate teachers beyond just a system of checkmarks," she said. "The new law is giving much more flexibility."

ESSA, signed by President Barack Obama last December, goes into effect starting with the 2017-18 school year. The law overhauls No Child Left Behind (NCLB) — President George W. Bush's 2001 reauthorization of the Elementary and Secondary Education Act of 1965 — and shifts accountability in elementary and secondary education from the federal government to states.

Many educators view ESSA as a welcome change to teacher evaluations under NCLB, because it is seen as an end to the era of significant federal involvement in teacher licensing and evaluation, according to NTC.

The primary goal of teacher evaluations is to ensure teachers are effective, which then improves student achievement. Under NCLB, that hasn't always been the case, Udall said.

"The research has shown that those methods simply have not been able to tell us which teachers are effective versus which are not," she said.

Under NCLB, states were required to meet the federal government mandates for education, although the government granted waivers to some states wishing to set their own standards. ESSA permits states to redesign and submit descriptions of their new accountability systems to the U.S. Department of Education, according to data from the National Education Association.

That includes districts' teacher evaluation systems.

ESSA does not require states to set up teacher evaluation systems based in significant part on students' test scores, which was a key requirement of NCLB. Under ESSA, states can develop their own goals and look at a broad range of factors to gauge student performance.

"The difference is under the new law teacher evaluation is being used to strengthen the profession, not necessarily sort and punish it," Udall said.

ESSA also encourages districts to have induction programs, which work with teachers to improve retention rates during their first two years. Udall noted that 1 in 5 teachers quits within the first two years on the job.

"A lot of it is new teachers really struggle to feel successful," she said. "If you feel successful in the first two years, you're much more likely to stay in it."

So an induction program during that time could make all the difference. NTC's own induction program works with about 10 percent of new teachers across the country.

"Our program focuses on this balance between managing a classroom climate," she said. "I don't care how good your training is, when you're standing in front of 30 live beings, it can be daunting for even the most trained teachers."

Udall, a former gifted education teacher, said if such mentoring programs had been around when she began her career, she would probably still be teaching.

"When I was a teacher, my principal would use an observation tool," she said. "And what I really needed was someone who would mentor and coach me to help me get better."

Observation and test scores will still be part of evaluations under the new law, though.

“I think why the new law was able to get bipartisan support is it married the idea of observation, test scores and other tools districts could now start to use,” she said. “It’s going to be really interesting to see how states respond and with more freedom, and how they address teacher effectiveness.”