Teachers are employees and not policy makers, if the policy of the school district is such that they are forbidden to correct spelling and math problems then no, their responsibility is to teach according to the accepted standard given them.
If you need them to spell then I would find the time, I did. I griped, cussed and complained to my wife and other parents the whole time, but just because the School Board's policy was to raise idiots, it wasn't mine.
I think you are missing my point, teachers do not have ultimate control over what they teach in their classes, nor how. Too many Federal and State mandates that over-rule their own preferences. As a teacher you are given the material, if that material states that you can not correct spelling or math mistakes then you can not do it, unless you want to be fired. All teachers are required to submit lesson plans to Administrators and have them approved prior to teaching a class, this is done on weekly or every other week basis.. Everyone gets mad at the teacher, but in most cases their hands are tied. In the case I provided, the teachers were very upset about the policy, but at the same time they could not go against the policy and correct the students as they would be in violation of the established standards and face disciplinary actions. How it was handled was that the teacher had to teach according to the policy set forth by the School Board, then after grading was completed she went over the answers that would be the correct answers as a group, that way the papers weren't corrected, and the kids at least got to see how it was supposed to be.
In the case of the original post I would find out why, but don't go in assuming that she used the word grate by mistake. I know it makes no sense, I know it is wrong to teach kids in this fashion, what I'm saying is that it is not always the teacher's fault. Just one of the many many reason I wouldn't teach kids, most of the reasons are not that teachers are incompentent, but the mandates forced upon them are. Like the "no child left behind" crap, all that law was about is teaching to the lowest common intelligence and instead of challenging kids to learn they make them lazy.