German flips English's own "ei"/"ie" rule
Every speller learns "i before e except after c" — and then German loanwords walk in and ignore it completely. That mnemonic was only ever about native English words like "believe" and "receive." German runs on a totally different, and almost opposite, pattern: "ie" is the one that says a long "ee," and "ei" is the one that says a long "eye." A speller who reaches for the English rule on a German word like "kaiser" will confidently say it wrong.
The rule
In German-derived words, "ie" represents a long-E sound (/iː/, as in "see"), while "ei" represents a long-I sound (/aɪ/, as in "eye") — sometimes a long-A instead, but never the long-E that English spellers expect from an "ei" spelling. "Kaiser" (a German emperor's title, the source of the word "czar") is pronounced "KY-zər," rhyming with "wiser" — not "KEE-zər." The "ei" is doing long-I work, the reverse of what "i before e except after c" would predict.
Hear the difference
Applying the English "i before e" pattern and reading "ei" as a long-E sound (like the "ei" in "receive"), instead of recognizing the German "ei" = long-I rule.
Try it yourself
"Diesel" — the engine and the fuel, named after German engineer Rudolf Diesel — uses the other half of this German pattern. Which pronunciation applies the rule correctly?