Imagine a child bringing home two totally different report cards.
One says she's getting straight A's. The other says she's failing.
Today's report, by the nonprofit group Education Trust, now says gaping disparities between state scores and national appraisals should serve as a warning to everyone that states have set the bar too low.
"If you want to know how well your youngster is being prepared for the 21st century, the results of the national assessment are much better than those of the state tests," said Katie Haycock, Education Trust director.
Take the fourth-grade reading test. Every single state reported better test results than the separate national test found. Thirty-eight states posted state test scores that were more than two times higher than the federal results.
Sometimes the gap between state and national numbers was as much as 60 percentage points. For example, Alabama reported that 83 percent of fourth-graders were proficient in reading. The national evaluation said that just 22 percent were.
Mississippi state results found 89 percent of students were proficient. The national score? Eighteen percent.
Georgia reported 87 percent of its fourth-graders were proficient, while the federal test showed just 26 percent were.
Why such a huge discrepancy? The state tests make it easier for children to shine.
"States worry about how much truth the public can handle without losing confidence in public education," Haycock said.
And under the No Child Left Behind law, there's a lot riding on those state test scores. Make the state test harder and you risk being sanctioned for having failing schools.
Georgia, with some of the largest discrepancies between state scores and national scores, has tried to improve its curriculum and its testing, said Kathy Cox, a Georgia school superintendent.
"We have a lot of work to do," Cox said, "and the good news in Georgia is we're already working hard on it. We're going to conquer it." The stakes couldn't be higher.
"We really need to stretch our kids," Haycock said. "Our competitors are stretching their kids. Other countries are, and if we're going to get competitive in the world we have to stretch."
ABC News' Kate Snow reported this story for "World News Tonight."