I taught for more than 30 years in a town in Rhode Island. When we had a strike, perhaps twice in my career, we had to make up the days we were on strike. So we were paid for the number of days in the school year which is set by the state. It didn't matter when those days were. Otherwise we would have been teaching on make-up days without being paid. I would call that slavery. The strikes in my school system were blessedly short. I think if we had been out for 10 school days we could have received "strike pay" from our union, but we would have had to pay it back when we resumed work. It's really a loan from a fund that we paid into with our union dues.