"Greedy teacher unions!" "Underperforming schools!" and many other simplistic slogans pollute the discussion about improving education. But more thoughtful people wonder how to counter all the other problems that make learning difficult: disinterested parents, bullies, too much testing, too little class time, and on it goes with things that are outside the control of teachers.
For a good summary of these problems, see "Teachers aren't the problem" by Micheal Kennedy, Star Tribune, 2007-06-17. Kennedy teaches at Southwest High School in Minneapolis.