Teachers unions: They're powerful, they're defensive, and they're stubborn. And if it seems their leadership places a premium on protecting its members ' above all other interests ' we should not be surprised, because protecting jobs and wages is what unions were created to do. And there's the rub, say critics who argue the unions are shielding too many teachers who do their jobs poorly ' teachers who should be replaced, for the good of the children. Indeed, so central is good teaching to good learning, some say it's the unions as presently constructed ' more than anything other factor ' that are undermining America's schools. But can it really be that simple? In a ranking of whom to blame for what's wrong in America's classrooms, do teachers unions really come before slashed budgets? Or crumbling infrastructure, broken homes and the influence of narcotics? Do bad teachers so outnumber good ones that the union represents a collection of educational misfits? The question comes down to a decision: do we need to reform the unions before we do anything else , and if we do, is that the fix that will once again make US public education the model system it once was?