I've had a similar situation but with a math teacher - they kept making mistakes the students would correct!!!!
I informed the headmaster. I told them that this was happening in the classroom and I would like to move my child to another teacher.
The headmaster wasn't too happy with my request but my child was moved to another class and did much better than before. I can't get the teacher fired or retrained but I can tell their boss ( the headmaster or mistress )

As another user suggested, you could always have your child moved to a different classroom.
However, if your child is not within the age range where they are learning how to spell themselves, I'd do nothing.
Keep in mind that your child's teacher is only human. No one's perfect or a pro at everything.
If it's causing an actual problem, have your child placed into another class.
If it's causing annoyance, let it go. They'll only be in that classroom a little longer.

If I got you right, you mean she does it repeatedly? Well, if that happens then I would move my child to another room or maybe school. Even if they're humans, they're teachers so they should teach correct spellings to children. Otherwise, they're not fit to be called teachers. That's why it is important to find good schools for children.

Being able to spell is not a mark of intelligence, it is an indication of someone who reads and recognizes sight words.

There are many English words that look one way but sound another (doubt and debt come to mind).
There are some English words that are spelled one way but have different meanings depending on the pronunciation (Polish for instance is a language/culture or what we dust furniture with; bow is something and actress takes at a curtain call or what little girls put in their hair.)
There are words that sound exactly alike but are spelled differently (their, they're, there).

English has spelling and pronunciation rules that really only work a percentage of the time.

Spelling in English is really more complicated than it looks.

Several questions come to mind. Does the teacher know his or her content? Is she a good teacher in all other respects? Does she listen to the students? Does she answer questions in a way that students understand? Is she available for help when students are struggling? These are more important issues than whether she can spell certain words.

If she is making mistakes while teaching, perhaps they are mistakes because she is going too fast. If they are mistakes on paper, then she didn't probably proofread well enough (not really a punishable offense in the grand scheme of life).

Teachers are people too. They make mistakes like everyone else. One of the previous posters even made a spelling/grammar error about a spelling question (though I'm sure he or she will say that he or she is not a teacher and therefore it's okay. Teachers have enough work to do without getting grief for incorrectly spelling a word.

I would be really surprised if this were an English teacher making these mistakes. Most likely it is another subject and the fact is that they probably don't and haven't read nearly as much as English teachers have in the past to develop spelling sense.