Here is my method to getting rid of bad teachers. The following is how the state I worked in got rid of bad teachers. It took them several years to get tenure. During those years they were observed several times unannounced by the principal, curriculum director and the superintendent. If they received 2 unsatisfactory ratings in a row, they were fired. After receiving tenure; we were observed several times a year. Some were 10 min drop ins and some were for the entire period. If we received 2 unsatisfactory rating in a row- we got our walking papers. Union or no union. The administration had to build a case showing either incompetence, illegal or immoral. I know of sever teachers that have been fired over the years I worked. I don't know how tenure works in other states. I know tenure for a college professor is totally different than state teachers in my state. So , In my state, it there are bad teachers- it's because the administration isn't doing it's job. Maybe it's time people got after the administration to get rid of bad teachers. Again, I speak of my state and don't know of others.