I wonder if this will have any effects for the European and later parliamentary elections. Is the labor movement typically considered strong in Poland?
Two main unions are extremely politicized and subservient to the political leaders. It's ironic the country where the Solidarity movement was born (note that present Solidarity has very little to do with the original movement's ethos, largely serving as PiS base, just like the OPZZ used to be a SLD base), the labor movement was largely neutered post-1989. The miners were an obvious exception, as they never hesitated to take to the streets.
But the fact the teachers, long considered as the least likely group to strike or aggressively exercise their goals, are going on a nationwide strike may very well show things are changing.