Teachers and other public education employees, such as community-college faculty, school psychologists and janitors, are quitting their jobs at the fastest rate on record, government data shows.

A tight labor market with historically low unemployment has encouraged Americans in a variety of occupations to quit their jobs at elevated rates, with the expectation they can find something better. But quitting among public educators stands out because the field is one where stability is viewed as a key perk and longevity often rewarded.

The educators may be finding new jobs at other schools, or leaving education altogether: The departures come alongside protests this year in six states where teachers in some cases shut down schools over tight budgets, small raises and poor conditions.

In the first 10 months of 2018, public educators quit at an average rate of 83 per 10,000 a month, according to the Labor Department. While that is still well below the rate for American workers overall—231 voluntary departures per 10,000 workers in 2018—it is the highest rate for public educators since such records began in 2001.

Sara Jorve, 43 years old, protested alongside other Oklahoma teachers last spring for better pay and classroom conditions. But the fifth-grade math and science instructor in Oklahoma quit in May after a dozen years in the profession. Ms. Jorve, a single mother, said her pay was so meager she was forced to rely on her parents for financial assistance.