"The No Child Left Behind law requires schools to meet annual goals largely based on student test scores. When schools fail to make "adequate yearly progress," the law assigns them a label and requires them to take certain corrective steps."
The article continues in outlining what needs to happen over the course of six years before a public school is required to actually do anything substantive.
6 years is half of your children's educational lifespan. We really can't afford to have our children be in a underperforming school because it will take too long.
When I was in 5th Grade I got bumped up, but only after the school year had started, I was totally bewildered by all the things they were talking about, while it didn't take me all that long to catch up, it was demoralizing at first.