WASHINGTON — Male teachers are an increasingly rare sight in the nation's public school classrooms.

Fewer than one in four — 24.5 percent — of the nation's instructors were men in 2004-05, the biggest gender imbalance in 40 years, according to a study released recently by the National Education Association, the nation's largest teachers union.

Money has a lot to do with it, said Brent Walker, principal of Haverhill Cooperative Middle School in North Haverhill, N.H., where men hold about a third of the teaching positions.

"The biggest part of it is the fact it's going to be very difficult to be the lead income earner in the family if you're teaching," he said. "I've had male teachers pull out of the interview process when they found out what the salary schedule was."

The NEA annual Rankings and Estimates report says salary is an issue, regardless of gender. Over the past decade, average teacher salaries increased by only 0.2 percent when adjusted for inflation.

The national average public school teacher salary for 2004-05 was $47,674. California ($57,876) and Connecticut ($57,737) ranked as the highest-paying states, while South Dakota ($34,040) and Mississippi ($36,590) were at the bottom, according to the union.

States showing the largest pay increases from 1994-95 to 2004-05 after adjusting for inflation were Louisiana (13.6 percent), Georgia (11 percent) and Idaho (9 percent). But inflation-adjusted salary went down in 28 states, including Wisconsin, New York, Hawai'i and New Jersey.

Higher pay probably would attract and keep more men, said Charlie Tolliver, principal of Vicksburg High School in Mississippi. Less than 18 percent of the state's teachers are men, the lowest rate in the nation.

But the former industrial arts teacher says he doesn't think a teacher's gender is that big a deal.

"If that person has the knowledge and the wherewithal to get the material across to (students), then it doesn't matter," Tolliver said. "The ultimate goal is the teaching and learning process."

Walker generally agrees but says there's probably some truth to research suggesting troubled boys may do better academically under male teachers.

"I think that we all have dealt with students who might have been able to have an easier time if they had a chance to connect with a male role model," the former English teacher said. "The more opportunities that we can create for those kids, the better."