Wechselpräpositionen
Nine prepositions switch case depending on the question they're answering: Dative when something is simply located somewhere, Accusative when something is moving toward a destination.
Ask wo? or wohin? before you pick a case
The same preposition, the same verb-family even, but the article changes with the question. Wo? ("where") wants Dative; wohin? ("to where") wants Accusative.
Die Katze liegt auf dem Tisch.
Die Katze springt auf den Tisch.
Same preposition, same table: dem Tisch (dative, already there) versus den Tisch (accusative, jumping onto it).
The Nine Two-Way Prepositions
These are the only prepositions in German that switch between Dative and Accusative depending on meaning; every other preposition always takes the same case.
The Verb Is Often a Clue Too
German has matched pairs of verbs: one describing a fixed state (goes with Dative), the other describing the motion that creates it (goes with Accusative).
| State (Dative) | Motion (Accusative) | |
|---|---|---|
| lying / laying | liegen | legen |
| standing / standing (something) up | stehen | stellen |
| sitting / seating | sitzen | setzen |
| hanging / hanging (something) up | hängen | hängen |
hängen is the odd one out: it's identical in both directions, so the case alone carries the meaning.
See It In a Sentence
The two-way preposition and its article are highlighted below, the same color coding used throughout every A2 lesson.
Das Buch liegt auf dem Tisch.
The book is lying on the table. (Dative: it's already there.)
Otto legt das Buch auf den Tisch.
Otto puts the book onto the table. (Accusative: motion onto the surface.)
Die Katze schläft in dem Korb.
The cat is sleeping in the basket. (Dative, often shortened to im.)
A Common Mix-Up
Don't decide the case by the preposition alone: in, auf, and the rest are two-way by definition, so the same word appears with both cases constantly. Always ask wo? or wohin? about the verb first, then pick the article that matches the answer.