I think unless the subject is English Language, spelling doesn't really come into it - otherwise you are saying that my dyslexic daughter should not get graded on content for Science/History etc because her spelling is atrocious.
My dyslexic friend says she needs things to be spelled correctly and to spell them correctly herself, otherwise the "hardwiring" that she has spent so many years battling with- to get those words into her head *correctly- has been in vain.
Godzilla - Having taught science myself I can confirm that children are not marked down on content/knowledge in exams etc if their spelling and grammar is not up to scratch, however, there is, or at least was, provision in coursework for 1,2 or 3 "additional" SPG marks (spelling punctuation and grammar)
Agree that teachers, from primary upwards, should set a good example!
I have walked past a shop today which had big hand written signs in the window saying
"SALE - MANY ITEMS REDUCED - TOP'S, SKIRT'S, TROUSER'S, COAT'S"
I had to come home for a --stiff drink-- soothing cuppa!