Microsoft Word's spellchecker flags many words that are spelled incorrectly, but it usually cannot identify words that are used incorrectly. Nearly 1/3 of SSU students' misspellings are homophone errors:
We should screen officers before they leave the seen. [Correct: We should screen officers before they leave the scene.]
The killers acted as if they new what was write and wrong. [Correct: The killers acted as if they knew what was right and wrong.]
When a student makes a homophone error, s/he uses the wrong word: a word that sounds just like the word s/he intended, but one that is spelled differently. We consider homophone errors misspellings (and do not place them in the "wrong word" category) because a student who makes such errors knows what word s/he wants to write. S/he simply does not know how to spell it.
Typos and Spacing Errors
The remaining spelling errors are nearly all "typos" (e.g.: the for then) or spacing errors:
Unlike children who do go to daycare, theses children have never earned to share. [Correct: Unlike children who do go to daycare, these children have never learned to share. Although the wordtheses clearly does not belong in this sentence, we consider this a misspelling or typo rather than a wrong-word error because it seems fairly obvious that the student would never say theses if she were reading this paper aloud; she simply never noticed that she accidentally hit the s key while keyboarding her work.]
Children who stay at home seem to be shy around other children and adults, where as kids who go to daycare centers tend to be more playful. [Correct: Children who stay at home seem to be shy around other children and adults, whereas kids who go to daycare centers tend to be more playful. ]
Pages 475-77 of The Longman Concise Companion provides a checklist for students who struggle with homophone errors.