Tests should track students' progress toward state standards, said Henderson, and those standards have to align with what students need to know to succeed in college or in the workforce. Without data to show that students are on track, it could be all too easy for disadvantaged children to receive a substandard education.
A similar logic drove No Child Left Behind through Congress in the first place. The law also set in motion a nationwide move toward standardized testing. State and local governments have added their own tests. Waivers from No Child Left Behind's requirements, granted by the Obama administration, push districts to add additional tests in order to evaluate teachers.
But many educators say that the current tests used to measure student progress—and hold schools and teachers accountable—don't measure learning well. "Standardized tests measure the wrong things," Stephen Lazar, a teacher at Harvest Collegiate High School, told the packed hearing room. They measure mindless repetition of facts, he said.
Pressure to raise student test scores can turn classes into cramming sessions. Lazar said he spends the entire month of May training his students to pass the Regents, New York state exams. "The learning and opportunity gap widens" when students with low scores spend so much time on test prep, while students with high scores can take on more complex assignments, he said.
Better assessments could, in theory, create better data. But it's hard for the federal government to address that problem. The United States doesn't have a national curriculum. Any federal attempt to create better tests would involve influencing their content and would be politically controversial.
The primary question legislators are debating now isn't whether standardized tests should exist, but whether the federal government should have so much control over them. A draft version of ESEA, circulated by Sen. Lamar Alexander, R-Tenn., would require states to submit test data less often, potentially from a patchwork of local assessments rather than a statewide test.
"I just don't think Washington has any business dictating to states and school districts what's best for the students that they serve," Sen. Pat Roberts, R-Kan., said at the hearing. Democrats, meanwhile, signaled that they feared the law gave states too much flexibility.
Jia Lee, a special-education teacher who testified on Wednesday, told Politico that the fight over testing is really about trust. "There needs to be more local autonomy, and what needs to change is the culture of 'the schools can't be trusted,' " she said.
That trust may be hard to win. While most Americans say they have confidence in their local school, the latest Gallup polling finds that just 26 percent of Americans have confidence in the public school system as a whole, down from 58 percent in the 1970s.