High test scores aren't the only thing that keeps schools off the state's underperforming list. Despite moderate goals that already allow about a third of students to fail state tests without impact, a set of mathematical formulas allows some Minnesota schools to meet even lower standards.

It's a common way for your child to be left behind: Even if a lot of kids are failing, a set of formulas helps their schools stay off the list.

Because officials were concerned that just a few students could skew an entire school's results, Minnesota uses a formula that further lowers the testing target for schools if they have an ethnically diverse population or a lot of students with special needs. The more groups a school has to count, the lower their required passing rate.

In 2004, 373 low-performing Minnesota schools avoided the "needs improvement" list because of the formula, state officials said. Many other states are doing the same thing.

How it works

Each school has a target passing rate for the tests, based on the number of kids who take the test and the number expected to score at grade level or higher. But schools with more poverty or more racial diversity also use a complicated formula to lower those targets.

The state sets rates for each school. These are the rates for Lincoln Elementary School in Bemidji:

Now, let's say that even after all of those adjustments, your child's school winds up on the list. It can do poorly and still get off the list the next year if it reduces the number of children scoring below grade level.

That's because the law is also based on improving from one year to the next. Schools can get off the list by showing a 10 percent improvement the next year, no matter how poor its overall performance is.

Here's how that formula works: For every student who scores at grade level or better, a school earns a point. For every student just below grade level, it gets a half-point. Kids far below grade level earn no points.

The goal: to improve the below-grade-level points by 10 percent.

Holland Elementary School in Minneapolis escaped the list in 2004 by cutting its below-grade-level points by 20 points, even though it fell short in reading in 2003 and 2004 for all its students:

2003 9148.1542.85

2004

7756 21