Our daughter over all is considered an excellent student. She taught herself to read and we did not even realize it.
When I asked our daughters second grade teacher about our daughters "poor spelling", she hemmed and hawed and finally spit out " I just think, "daughter" is not a natural speller."
I am not sure why I would be surprised. I also am a terrible speller. Sometimes even word check cannot figure out what I am trying to spell!
My husband on the other hand is excellent. Our daughter has worked very hard to be a better speller, I gave up a long time ago..
One of the things we used to do to help our daughter study for spelling tests, was to have her give us, spelling words, then she had to go back and check our work.
Of course the repetition of writing out a word, and the repetition of calling out a word and having her spell it on paper, spelling it out aloud and sometimes, handing her a book and having her search for the word.. also helped her.
Once she was a bit older, we kept a "Word a day Calendar" on the one bathroom we all share. We would each try to learn the definition of the word word, try to learn to spell the word.. and then use it in sentence that day.