There is something appallingly cynical about teachers going on strike.
Unions and collective bargaining in general serves two basic functions: protecting labor from abusive actions on the part of employers and enabling workers to share in the profits that a company makes.
As we saw with the American auto-makers, corporations that make collective bargaining agreements that are detached from the profitability of the company will eventually have to pay the piper. The problem was further exacerbated by the fiscally imprudent concession of defined-output pensions in lieu of defined-input retirement accounts.
The public sector unions have four problems, the first two are related to the problems that GM exemplified: they are fighting to keep defined-output pensions at a time when most people recognize the impracticality of funding those pensions and they do not contribute to profitability because governments are not profit-making enterprises.
The third reason is related to the second: governments are bureaucracies that are unrelated to profit-making. In bureaucracies of that nature, experience indicates that status quo is a stronger imperative than efficiency or effectiveness. That is to say, public employees protected by unions are virtually irreplaceable, not because of their talents but because their is no need to protect a profitability bottom-line and therefore little incentive to rock the boat by cutting deadweight.
Finally, there is the not insignificant matter of morals. Being a paid public servant is implicitly a conflict-of-interest. By definition, public servants exist to provide services to the public. Many of these services, such as teaching, are essential. Public servants, then, have a great deal of clout simply by the fact that the public needs them to keep doing what they are doing. If an autoworker goes on strike, not many private citizens will feel any impact and if they do it would probably not be immediate; if teachers go on strike, almost everyone feels it and immediately.
Public employees have every right to air grievances. But if a public servant gets to the point in which he is willing to go on strike, then he has placed in own best interests over those of the public and has ceased to be a public servant. When a teacher ceases to be a public servant, it is time to get rid of him.