While moonlighting isn't unique to teachers, they do tend to have second or third jobs at a higher rate than other professionals.

By day, Wade Brosz teaches American history at an A-rated Florida middle school. By night, he is a personal trainer at 24 Hour Fitness.

Brosz took the three-night a week job at the gym after his teaching salary was frozen, summer school was reduced drastically, and the state bonus for board certified teachers was cut. He figures that he and his wife, also a teacher, are making about $20,000 less teaching than expected to, combined.

“The second job was to get back what was lost through cuts,” said Brosz, a nationally board certified teacher. “It was tougher and tougher to make ends meet. I started personal training because it’s flexible hours.”

[Read: “Hey, teachers: The Heritage Foundation thinks you’re overpaid.”]

Second jobs are not a new phenomenon for teachers, who have historically been paid less than other professionals. In 1981, about 11 percent of teachers were moonlighting; the number has risen to about one in five today. They are bartenders, waitresses, tutors, school bus drivers and even lawnmowers.

Now, with the severe cuts many school districts have made, teachers like Brosz, who hadn’t considered juggling a second job before, are searching the want ads. The number of public school teachers who reported holding a second job outside school increased slightly from 2003-04 to 2007-08. While there is no national data for more recent years, reports from individual states and districts indicate the number may have climbed further since the start of the recession.

In Texas, for example, the percentage of teachers who moonlight has increased from 22 percent in 1980 to 41 percent in 2010.

“It’s the economy, primarily,” said Sam Sullivan, a professor at Sam Houston State University, which conducts the survey.

Rita Haecker, president of the Texas State Teachers Association, said cuts in education have forced many teachers to take furlough days. It’s an extra strain because, unlike in the past, many teachers are now the primary breadwinner, either because they are a single parent or their spouse is unemployed, Haecker said.