WASHINGTON (AP) -- The federal No Child Left Behind law says that by the 2013-14 school year all students must pass state tests in math and reading.

About half of the states have steady annual goals for increasing the percentage of students passing, or working at their proper grade level. But according to a report by the nonpartisan Center on Education Policy, the other half set the bar very low early on, so now expect big annual achievement gains.

The Center says it's unlikely that states taking that approach can make the kind of gains expected.

Educators say the strategy is like a balloon mortgage payment, in which home owners have a final payment that's much larger than previous ones.

The Education Department says nearly 11,000 schools, or a little more than 10 percent of all public schools, have missed their state-set progress goals and are taking corrective steps.

Schools that don't hit testing benchmarks for two years or longer face increasingly stiff consequences -- such as having to transport children to higher-performing schools or paying for tutoring to replace staff thought to be a part of the school's problems.