If you think teacher only work 9 months a year you really need to do more research on your new profession. If your school only has you with students 5 hours a day then let me know where you are at so I can get my resume out to your HR people (just kidding). Make sure you realize that you will be the lowest paid licensed professional. You will also be the scapegoat for all the failures of the educational system. Student, Parents, unemployment and the general breakdown of the family and society will never be mentioned.
So yeah...5 hours a day with students, unless they're doing tutoring or detention or something after school. And you really do get a couple months of completely free time in the summer, if you plan right and you want it. My mother's been a kindergarten teacher for I don't know how long, and my aunt is a high school music/english teacher, and both of them rave about summers off. Sure, there's reading and lesson planning to some extent, but in no way is it 40+ hours a week like the rest of the world works.
And they are only the "lowest paid" if you think the only compensation you get for a job is a paycheck. My idea of total compensation includes salary, sure--but it also includes vacation time, retirement planning, travel time, flexibility, ease of having a family and working full time, level of autonomy, benefits, and the intangible things like feeling good at the end of the day because you made a difference. You don't get that in most professions. If your salary was the only type of payment anyone got for a job, we'd all be corporate attorneys or investment bankers! Very little job satisfaction, zero time off, and no flexibility--but you sure do get rich!
There are no shortage of people wanting to become teachers. And it's not like they lied to us when we applied for teaching school, and told us we'd make 6 figures!