S
schedule If perfecting your spelling is on your schedule, remember the [sk] is spelled as in "school." (If you use British or Canadian pronunciation, why do you pronounce this word [shedyul] but "school," [skul]? That has always puzzled me.)
separate How do you separate the [e]s from the [a]s in this word? Simple: the [e]s surround the [a]s.
sergeant The [a] needed in both syllables of this word has been pushed to the back of the line. Remember that, and the fact that [e] is used in both syllables, and you can write your sergeant without fear of misspelling his rank.
supersede This word supersedes all others in perversity. As if we don"t have enough to worry about, keeping words on -ceed and -cede ("succeed," "precede," etc.) straight in our minds, this one has to be different from all the rest. The good news is: this is the only English word based on this stem spelled -sede.