the plural in German is "Knöpfe" (alternativ if you need to write the word on a computer without the "ö"-button, than it's written "Knoepfe")
German plural forms are formed irregularly.
The noun computer is the singular form; the plural form is computers.
The plural for computer is computers.
The plural of computer is computersand the plural of is is are, e.g. the computer is expensive: the computers are expensive.
German shephards.
The plural form of the German word Wohnwand is Wohnwände
The plural of Fach is Fächer.
das Poster (singular) die Poster (plural)
Using the correct title "German shepherd dog" makes easier. The plural is then "German shepherd dogs". They are however incorrectly called "German shepherds"
Kugelschreiber is both the singular and plural.
Its the Same word. The plural of schüler is schüler