4. Case: the core idea

Case answers one question: what role does this noun play relative to the verb or the preposition that governs it? German marks four roles, and you already use all four in Azerbaijani; the difference is that German puts the marker on the article in front of the noun instead of a suffix at the end.

The four cases mapped to what you know

Case	Question word	Role	Azerbaijani	German example
Nominativ	wer? was?	Subject: the one doing or being	adlıq hal (no suffix)	Der Mann schläft.
Akkusativ	wen? was?	Direct object: the thing directly affected	təsirlik hal (-ı, -i, -u, -ü)	Ich sehe den Mann. (Mən kişini görürəm.)
Dativ	wem?	Receiver, beneficiary, experiencer; also after many prepositions	yönlük hal (-a, -ə), for the receiver	Ich gebe dem Mann das Buch. (Kitabı kişiyə verirəm.)
Genitiv	wessen?	Owner, “of”	yiyəlik hal (-ın, -in)	das Auto des Mannes (kişinin maşını)

The question words carry the same endings as the masculine article: wer / der, wen / den, wem / dem, wessen / des. That r–n–m–s sequence is the backbone of the whole system.

Three traps from Azerbaijani

1. German marks every direct object, definite or not. Azerbaijani marks only the definite one (kitab oxuyuram vs kitabı oxuyuram). German says Ich lese einen Roman and Ich lese den Roman; both are Akkusativ.
2. Your locative and ablative cases are German prepositions + Dativ. şəhərdə = in der Stadt; şəhərdən = aus der Stadt. German has no separate case for “in” or “from”; the preposition does that job and demands Dativ.
3. Your dative of direction is NOT German Dativ. şəhərə (to the city) = in die Stadt, which is Akkusativ. Direction toward a place uses a two-way preposition + Akkusativ, or nach / zu + Dativ (section 6). Map by role, not by suffix.

Why only masculine seems to change

In the feminine, neuter and plural, Nominativ and Akkusativ look the same (die / die, das / das). Only the masculine shows the difference: der → den, ein → einen. So almost every Akkusativ error you make is a masculine noun; check those first.

What assigns case: five triggers

1. The verb’s role structure. The subject is Nominativ. A verb with two objects usually takes the person in Dativ and the thing in Akkusativ: Ich erkläre dem Kollegen den Plan.
2. Verbs that take only a Dativ object. The person is not acted on but receives or experiences something: helfen, danken, gefallen, gehören, folgen, antworten, glauben (jemandem), gratulieren, passen, schmecken, fehlen, vertrauen, begegnen, zuhören, widersprechen. Ich helfe dir (you receive help).
3. Prepositions (section 6). The preposition, not the verb, decides the case of its noun.
4. Fixed verb + preposition pairs (section 9): warten auf + Akk, Angst haben vor + Dat.
5. Other triggers: time expressions without a preposition are Akkusativ (jeden Tag, nächsten Montag, den ganzen Abend); some adjectives take Dativ (mir ist kalt, jemandem dankbar / ähnlich / bekannt).

One exception catches many learners: sein, werden, bleiben and heißen link two Nominatives. Er ist ein guter Lehrer (not einen guten). Nothing is being acted on; both nouns name the same person.

Genitiv today

In speech, Genitiv is mostly replaced by von + Dativ: das Auto von meinem Bruder. In writing and at C1 you need it: possession (die Ergebnisse der Studie) and the Genitiv prepositions wegen, trotz, während, statt, innerhalb, außerhalb, aufgrund.

The decision procedure

[embedded content: case decision · 6 questions, stop at the first yes]

Work down from the top and stop at the first yes. The order matters: whenever a preposition governs the noun, it overrides the verb.