Hartford (AP) - Nearly half of Connecticut public schools did not meet improvement standards this year under the No Child Left Behind Act, whose benchmarks have become tougher than ever to reach as federal officials push Congress to overhaul the law.

The state Department of Education said Monday that 47 percent of Connecticut's schools fell short of making "adequate yearly progress," or AYP, because their students' scores either did not improve at all, or did not improve enough to match the federal law's requirements.

That percentage is up from last year, when 28 percent of Connecticut schools fell short of the AYP benchmarks. AYP is calculated based on test participation, academic achievement, graduation rate and other statistics. But every few years, the percentage of students who must pass state tests increases.

State education officials said students are generally performing slightly better and the test results reflect a change this year in federal benchmarks. The department is trying to help 18 of the state's largest districts improve schools that have been struggling for years, Acting Commissioner George Coleman said.

"It is very difficult to overcome the effects of poverty with limited school resources, but our work to employ effective strategies that help close the gaps in student performance is beginning to show results," Coleman said.

The number of schools deemed as "in need of improvement" - meaning they didn't meet federal benchmarks for at least two consecutive years - dropped from 343 to 330, or about 34 percent.

Parents can seek special tutoring for their children or request transfers to better-performing schools if their neighborhood school is "in need of improvement," but the transfer rate is very low.

Some parents and educators have said that is because many neighboring schools are also in need of improvement, particularly in poor urban districts, so families tend to keep their children in a familiar school rather than move them to another whose performance is no better.

Progress requirements nationwide under the 2002 law will become more stringent each year through 2014, when all students are expected to be proficient on state reading and math tests.

Several states are asking the U.S. Department of Education for waivers, saying the goal is impossible to reach without significantly more funding. Connecticut officials said last month they were considering whether to request a waiver.

Education Secretary Arne Duncan and the Obama administration want the law overhauled, but Congress has not acted on the request. Duncan has warned Congress that up to 82 percent of America's schools could be labeled as "failing" this year because of the ever-increasing benchmarks.

Connecticut's experience with the federal regulations has produced mixed results.

In 2007, about one-third of Connecticut's schools fell short of performance goals. The number jumped to 42 percent in 2008 and dipped slightly to 40 percent in 2009. Last year, it was down to 28 percent.

One complicating factor is that even schools making strong progress can be labeled as failing to meet AYP if that growth isn't quite enough, or if it's considered too slow among subgroups such as special education students or those for whom English is not their native language.

In the past, that's placed some schools on the watch list even in upper middle-class or affluent districts, including Greenwich, Glastonbury, Cheshire and Monroe.

"I think the AYP has to be taken with a real grain of salt," said Casey Cobb, director of the Center for Education Policy Analysis at the University of Connecticut.

Cobb, who is also an associate professor and head of UConn's Department of Educational Leadership, said that in addition to the difficulty of reaching ever-shifting benchmarks, the tests on which No Child judges schools' quality is just a snapshot of a moment in time. A better way to judge them would be to follow individual students' progress over time, he said.

The label that a school is "failing" can also be painful for the community, he said, especially if they have made academic progress but still are designated as falling short.

"For the schools themselves and the teachers and administrators in them, I think it's demoralizing," Cobb said. "Morale is immediately lowered in those instances, and it may also cause behaviors that don't lend themselves to good teaching and learning in the long term because there are these short-term pressures to increase the test scores."

This year's list of Connecticut schools "in need of improvement" is heavily populated with urban schools and those in adjacent blue-collar suburbs, including some that have fallen short for eight years or more.