For almost 40 years, the federal government has been helping foot the bill for special education, paying part of the nearly $80 billion annual tab to educate millions of children with disabilities.

But the system has gotten expensive and overcrowded, and critics say many of its 6 million kids don’t really belong in special ed.

"Special education unfortunately has become a dumping ground for students who are difficult to teach, for students who don't quite meet the standard mold that is convenient for the general education classroom," said Marie Gryphon of the Cato Institute.

Half of all special ed students are now identified as learning disabled, which sometimes simply means they haven’t yet learned to read.

In fact the number of children classified as learning disabled students has grown more than 300 percent in the last 26 years.

There are several reasons for the spike, critics say. In certain cases, schools want the extra money that comes in for special education and learning disabled programs. In other cases, children are misdiagnosed just because they’re having trouble learning or are misbehaving in class. And in still other instances, parents are taking advantage of the system.

"Often, affluent parents will not only allow but encourage diagnosis of their child as learning disabled because it does come with special attention and extra tutoring services," Gryphon said.

The Department of Education agrees that more needs to be done.

Robert Pasternack, assistant secretary of education, said the situation presented a big challenge for the department to do a better job of assessing children so that they get the kind of schooling that’s appropriate for them.

President Bush wants to help, too, and has called for a simpler, fairer, more effective special ed system. Teachers say their main concern is that resources and attention be refocused on the students who really need them.

Fox News' Catherine Donaldson-Evans contributed to this report.