As in the past, girls did much better than boys at both grade levels. Eighth-grade English teacher Amanda Avallone, a member of the board that administers the national test, said the gender gap "troubles and mystifies" her.
"Nothing in my experience tells me that boys can't write," said Avallone, of Boulder, Colo. She said expectations appear to be lower for boys when it comes to writing.
Overall, eighth-grade scores rose modestly from the last time the test, known as the Nation's Report Card, was given in 2002.
The proportion of kids scoring at or above the basic level rose from 85 percent to 88 percent. At that level, students show they can use grammar, spelling and punctuation that are accurate enough to communicate to a reader, but there may be mistakes in their work that get in the way of its meaning.
The percentage of eighth-graders at or above the proficient level - which policy makers call the goal - was unchanged from five years earlier. About a third of eighth graders achieved the "proficient" label.
If there are errors in the writing of an eighth-grader working at the proficient level, they're not serious enough to get in the way of the work's meaning.
State and federal efforts to improve education have focused intensely on poorly performing students in recent years said Michael Petrilli, vice president at Thomas B. Fordham Institute, a Washington-based education think tank. He said the trend helps explain why more kids can now handle basic writing, while there's been no growth in the percent of top achievers.
"It's good news that the lowest achieving kids are seeing some gains," he said. "The problem is in a competitive world we need to pay attention to all of our kids, including those at the top."
The eighth-grade test results were broken down by state. North Carolina was the only state to see scores go down compared to 2002.
The test given to high-school seniors wasn't broken down by state.
Nationally, the percentage of 12th-graders scoring at or above the basic level showed a more dramatic jump, rising from 74 percent to 82 percent from 2002 to 2007.
That kind of progress hasn't generally been seen among high-school seniors in other subjects, said Mark Schneider, commissioner of education statistics at the Education Department.
One possible reason for the solid improvement in 12th-grade writing may have to do with the SAT exam. A writing portion was added to the college entrance exam in 2005, and since then teachers report greater focus on writing in their schools, according to a survey by the College Board, which runs the SAT.
There was no increase in the number of 12th-graders working at or above the proficient level since 2002, similar to the results for eighth-graders. About a fourth of 12th-graders are considered proficient writers. At that level, students know how to write a clear introduction and conclusion, among other things.
"Writing is a fundamentally important task," Schneider said. "We still have a long way to go, but American students have gotten better."
