Summers...
Some teachers work, some go to school, and some relax. Yes teachers receive a salary, but that salary is based on the fact that they don't work summers. If schools systems decided to switch to year round learning, I would imagine that teachers would have to be paid more. All teachers are required to do a certain amount of training/classes (by hour or credit depending on the state or system) in a certain time period to keep their license. This can be done after school or during the summer. Some teachers might chose to have longer days during the school year so they can enjoy the summer off. Not all colleges offer courses (that are part of earning an additional degree) that match up with a teacher's actual time off during the summer. Also there are lots of teachers who come in early in the summer to get their classroom set up. There are lots of teachers who work weekends or after school hours to have their lessons up to date. All that is in addition to meetings, conferences, etc. If you were to add up the extra hours it would be pretty close to the time off during the summer. That being said, I'm sure there are some teachers who do the very minimal and put almost no extra time in what so ever, but its unfair to lump all teachers in such a group.