Chapter 12-1: Spelling words with "ei" and "ie"
When the sound is a long "e" (as in feed), write "i" before "e", except after "c". After "c" reverse the spelling ("ei"):
After other letters
believe, yield, reprieve
After c
ceiling, perceive, conceit
The problem with this rule is that it works only when "ei"/"ie" sounds like the "ee" in feet. If it has any other sound, you should write "ei" even after letters other than "c":
foreign, vein, freight