But whether that's due to the federal education law is still unclear, according to the Center on Education Policy report. Jack Jennings, president and CEO of the center, said either way it's good news for the country.
"I think it's reasonable to assume kids know more," Jennings said.
NCLB, which was signed into law in 2002, requires schools to work toward making sure every child tests on grade level in math and reading by 2014. Some schools that don't make enough progress toward that goal face sanctions.
In Utah, students scored higher on state math and reading tests between 2004 and 2007. The state had mixed success, however, in narrowing achievement gaps between some groups of students. The gaps between white and Latino students, white and black students, white and American Indian students, and low-income and other students all widened in some respects and narrowed in others, according to the report.
Nationwide, achievement gaps between groups of students narrowed more than they widened, according to the report.
The Center for Education Policy originally set out to determine whether NCLB has affected achievement nationwide. But the center soon learned that was "impossible," according to the report.
It's impossible to tell whether NCLB has boosted achievement because states, school districts and schools have made many other changes since 2002 that also could have played a role, according to the report. Also, every school has been affected by NCLB. There's no control group with which to compare students who have not been affected by NCLB.
Jennings said test scores nationwide might have improved due to a number of factors. Maybe it's because students are getting better at taking standardized tests. Or, maybe it's because schools have been spending more time on math and reading, he said.
State Associate Superintendent Brenda Hales agreed it's unclear whether NCLB has made Utah students better at math and reading. She said NCLB has been positive, however, in that it's prompted educators to look more closely at the performance of each student.
Under NCLB, groups of students within a school - such as black, Latino, Asian, low-income and disabled students - must make a certain amount of progress toward proficiency each year. If one group fails to make enough progress, the whole school can be sanctioned, so schools must focus on every group.
"There's no doubt about it that No Child Left Behind has had an impact," Hales said. "At the very least it's helped educators take a look at tests scores by looking at groups rather than the whole."
But many people criticize NCLB for taking away local control, forcing schools to focus heavily on testing and for labeling entire schools as failing when just one group isn't meeting goals.
Andrew Coulson, director of the Cato Institute's Center for Educational Freedom, criticized the report released Tuesday for leaving out information about how the U.S. has done on international tests since NCLB began.
