German Grammar Explained /

Adjective declension after indefinite articles

This is adjective declensions: part II. Let's dive into them very quickly! Quick and painless!
Part II is about how to decline adjectives after the indefinite articles ein/eine and also, very handily, the negation word kein, which turns out to be the same.
der Mond
ein schöner Mond kein schöner Mond
die Blume
eine schöne Blume keine schöne Blume
das Lied
ein schönes Lied kein schönes Lied
die Stifte
-- schöne Stifte keine schönen Stifte (!)
Unlike when declining adjectives after definite articles (der schöne Mond), when we decline adjectives that follow indefinite articles, the gender has to be marked somewhere, that's why it appears in the adjective ein schöner Mond. Makes sense, right?