Every teacher I know works far more hours than we get paid for. Myself, I arrive at school an hour early every single day, and quite often I work late. I also work through lunch. That means I "donate" at least 2 hours a day for 180 school days. After some quick math, that comes out to 45 days of unpaid work. So much for a "paid summer vacation."
The kids get 10 weeks of break, but I'll start back after 9 weeks in order to get my room set up and make lesson plans. Over the summer I am also taking a 45-hour class in June (that cost $343) and another two days of classes offered by my district in August, all for "professional development."