http://mowicpopolsku.com/polish-grammar/cases/nominative/#noun-plural The rule: Attach -(i)e when Masculine nous with the stem ending with soft consonants (-ć, -dź, -ś, -ń, -ź) as well as with -c, -dz, -cz, -dż, -sz, -ż, -rz, -l, -j. lekarz – lekarze nauczyciel – nauczyciele klucz – klucze

Susanne, Polish is very logical, if you dig deep into its history. But even without digging it is possible to just relax about all the rules and enjoy the beauty of this language. :-)

List of the endings for plural masculine personal nouns: nominative ~i (~y), ~e, ~owie, ~a I can't think of a Polish word that would have 'i' after 'rz'. Nauczycieli is reserved for genitive and accusative hence nauczyciele. The same with model-modele, przyjaciel-przyjaciele. Here is a link to some grammatical tables with endless endings, if you enjoy tables: http://grzegorj.interiowo.pl/gram/deklin00.html All the best!

Hahah, we don't know! Seriously, polish is so inconsistent! BUT "nauczycieli" is a other grammatical case.

I'm also looking forward to the answer to this one. Personally, I tend to think that the reason is just because. Because nothing, absolutely nothing about the Polish language is ever regular or logical. That's what makes it so uniquely beautiful :)