Refer to this chart as a guide for adjective endings:
| masculine | feminine | neuter | plural | |
| nominative | (r) | e | (s) | e |
| accusative | n | e | (s) | e |
| dative | m | r | m | n |
| genitive | s | r | s | r |
Wait, what?! Why are there parentheses? What does that mean? What am I supposed to do? Ahhhhh!
Fear not, my pupils of philology! There are little things called ein words, and they pretty much explain themselves. These are the adjectives that end in -ein, of course, but they also include a few other words that follow that pattern:
kein, mein, dein, sein, unser, euer, ihr, Ihr, and let's not forget ein.
These words are the ones to which those parenthesized letters do not apply. Or the ones to which the parentheses do apply.
In other words, you would never use "einer" to modify a noun in the nominative case.
Okay... can you give an example?
Ein Bus kommt. (A bus is coming.)
Eine Blume wächst. (A flower is growing.)
Now, I'm pretty sure the nominative case is not what you came here for.
So, my friends, stand by and watch some grammatical linguistics. I'll try to keep the examples basic so that you can see what's being explained without worrying about other rules.
Side note: when you have an adjective in the predicate, it's called a predicate adjective. You wouldn't believe how creative grammarians are when they name things. In predicate adjectives, you don't worry about cases. The case is nominative, although it is probably easier to think of it this way: just use the stem of the adjective, with no endings.
The bus is yellow. Der Bus ist gelb.
The tree is tall. Der Baum ist groß.
Get it?
Nominative.
masculine: Der Tisch ist rund. The table is round. Ein Bleistift ist spitz. A pencil is pointy.
feminine: Die Frau ist klug. The woman is smart. Eine kluge Frau schreibt. The smart woman is writing.
neuter: Das Wetter ist schön. The weather is nice. Ein Auto fährt. A car is driving.
plural: Keine Fische sind Säugetiere. No fish are mammals. Rote Schuhen sind schick. Red shoes are cool.
Accusative.
masculine: Ich habe einen Bruder. I have a brother. Du hast den Pulli. You have the sweater.
feminine: Du hast die Tasche. You have the bag. Ich habe deine Jacke. I have your jacket.
neuter: Hast du das Geld? Do you have the money? Ich habe ein Buch. I have a book.
plural: Du hast die Blumen. You have the flowers. Wir haben keine Papiere. We don't have (any) papers.
Dative.
masculine: Ich gebe meinem Bruder Geld. I give my brother money. Du gibst dem Lehrer einen Apfel. You give the teacher an apple.
feminine: Du gibst der Lehrerin einen Apfel. You give the teacher an apple. Wir geben einer Klasse eine Tour. We give the class a tour.
neuter: Ich gebe dem Restaurant mein Geld. I give the restaurant my money. Wir kaufen dem Kind Shuhen. We buy the kid shoes.
plural: Wir bringen den Kindern Süßigkeiten. We bring the kids candy. Wir bringen keinen Kindern Kuchen. We don't bring kids cake-- literally "We bring cake to no children."
Genitive.
masculine: Das ist der Hand des Lehrers. That is the teacher's hand. Der Bruder meines Vaters ist mein Onkel. The brother of my father is my uncle.
feminine: Meine Tante ist die Schwester meiner Mama. My aunt is the sister of my mom. Die Blätter der Pflanze sind essbar. The leaves of the plant are edible.
neuter: Die Blätter des Buches sind dick. The pages of the book are thick. Die Handlung meines Lieblingsfilms ist lustig. The plot of my favorite film is funny.
plural: Die Lehrer dieser Schulen sind nicht zufrieden. The teachers at these schools are not happy. Die Eltern meiner Eltern sind mein Großeltern. The parents of my parents are my grandparents.
