In the run-up to the Chicago teachers strike, the union and its political supporters made claims about teacher compensation that don’t comport with reality. No one expects a major political conflict to be conducted like an Oxford Union debate, but public-sector unions have an unusual stubbornness when it comes to repeating “facts” that aren’t true.

First, are teachers generally “underpaid?” The average salary for a public-school teacher, around $55,000, is by no means spectacular. But the retirement and health benefits enjoyed by teachers are several times greater than what private-sector professionals receive. By the standard of a comparably skilled private-sector professional, the average public-school teacher is overpaid, not underpaid. And the Chicago Teachers Union is on even shakier ground with their “underpaid” claim. Salaries for Chicago teachers are among the highest in the nation.

Second, do teachers work extremely long hours? In answering critics of Chicago’s unusually short school day, teacher advocates have cited their extensive work at home and on weekends. Teachers do work off-hours, but so do many private professionals. Including work time wherever and whenever it takes place, teachers work no more than (actually slightly less) than white-collar professionals in other fields.

Third, does granting less-than-requested pay raises risk losing teachers to more lucrative private jobs? Actually, only about 1 percent of teachers leave the profession for a job in a different field each year. Those that do leave make less on average in their new jobs, not more.

If teachers unions acknowledged these facts, it would be difficult for them to justify a strike. So, out go the facts.

— Jason Richwine is senior policy analyst in empirical studies in the Heritage Foundation’s domestic-studies department.