This image has being going the rounds for some time now and it bothers me because (a) I have been on both sides of that desk and (b) it misses the point about teachers and parents. Teachers and parents are on the same team: team "Make it possible for your child to be happy and successful".
Someone in a comment thread for asked me about becoming a teacher: whose fault is it if a child gets bad marks?
This was my reply
It's a fabulous job, but very, very demanding. I think it is not really useful to talk about whose "fault" it is if teaching a child did not succeed. I have students who it is hard to get through to, but that is actually the job: I am trying to present material and diagnose problems in understanding the material in ways that will work for all my pupils. If that did not work it is a function of my presentation, the medium it passed through and the ability of the student to receive it.
I do not always succeed, in getting through because the task is complex and it changes for every student in every lesson and literally with the weather outside: try teaching exponents to tired teens on a Friday afternoon after they got cold and wet and had a tough gym lesson. Try understanding factoring quadratics when the boy you like is obviously obsessed with your best friend.
I have found parents to be supportive and helpful and they have found me to be an absolute fan of their child rather than a harsh critic. I have been on the other side of the table and loathe those conversations in which a frustrated teacher is unloading about a classroom situation that you have never experienced at home.
A class recently said to me, in several individual voices, "we are a not a very nice class are we?" and I responded with all the passion and conviction that I possess that I liked them very much, that we did not always get on behaviour-wise, but that did not mean that they were not great kids and fun to know.
If you do decide to become a teacher, be aware that it will draw on your deepest reserves and teach you a good deal about the kind of person you really are. It gets very close to home and you will sometimes shed tears of all kinds.