In our biggest school systems, it’s become virtually impossible to fight the teachers unions and fire bad teachers. The giant Los Angeles Unified school system, with 33,000 teachers, fires only about 21 a year, or fewer than 1 in 1,000, according to the findings of an L.A. Times investigation. Now either Los Angeles has the greatest teachers in the world or something is very wrong. Talk to parents and you’ll know the answer.