We have already learned that some prepositions in German are always followed by an object in the accusative case, while others are always followed by an object in the dative case.
A third group, called the "two-way prepositions" (Wechselpräpositionen), all show spatial relationships. They are followed by the accusative case when they signal movement, and by the dative case when they signal location.
In the example sentences in the table below, notice how the verb determines movement or location. Verbs such as sein, liegen and stehen show location and thus require the dative case; verbs such as gehen and fahren show movement and thus require the accusative case.
The German flag Grammar 7: Die Wechselpräpositionen
an
Kevin geht ans Fenster. (Acc.)
("Kevin is going towards the window.")
Kevin steht am Fenster. (Dat.)
("Kevin is standing at the window.")
auf
Ich gehe auf die Post. (Acc.)
("I'm going to the post office.")
Das Buch liegt auf dem Tisch. (Dat.)
("The book is on the table.")
hinter
Franziska läuft hinter die Post. (Acc.)
("Franziska runs behind the post office.")
Der S-Bahnhof ist hinter der Post. (Dat.)
("The S-Bahn station is behind the post office.")
in
Sie müssen in den ersten Stock gehen! (Acc.)
("You'll have to go to the first floor.")
Damenjacken finden Sie im dritten Stock. (Dat.)
("You'll find ladies jackets on the third floor.")
neben
Ulla legt die Zeitung neben das Buch. (Acc.)
("Ulla puts the newspaper next to the book.")
Das Schloss liegt neben dem Blumengeschäft (Dat.)
("The castle is next to the florist's.")
über
Wir fahren über die Brücke. (Acc.)
("We're driving over the bridge")
Es gibt Wohnungen über dem Blumengeschäft. (Dat.)
("There are flats above the florist's.")
unter
Das Kind läuft unter das Bett. (Acc.)
("The child runs under the bed.")
Die Katze liegt unter dem Bett. (Dat.)
("The cat is lying under the bed.")
vor
Der Bus fährt vor das Hotel. (Acc.)
("The bus drives up in front of the hotel.")
Der Bus ist vor dem Hotel. (Dat.)
("The bus is in front of the hotel.")
zwischen
Ich laufe zwischen das Reisebüro und die Sparkasse. (Acc.)
("I'm running between the travel agency and the savings bank.")
Die Post ist zwischen dem Reisebüro und der Sparkasse. (Dat.)
("The post office is between the travel agency and the savings bank.")
This does not mean however that all prepositions of motion take the accusative case. We have already seen that "aus", "nach", "von" and "zu" always take the dative case, even when they indicate motion. It is much better to remember the three different groupings which we have encountered so far:
The German flag Grammar 8: Prepositions and cases
Accusative
(bis, durch, für, gegen, ohne, um)
Dative
(aus, bei, gegenüber, mit, nach, seit (= since), von, zu)
"Two-way" prepositions
(an, auf, hinter, in, neben, über, unter, vor, zwischen)
Merging of prepositions with the definite article
We have already seen in an earlier chapter that certain prepositions tend to merge with the definite article in the dative case. This is also true with certain prepositions in the accusative case, although fewer prepositions require this contraction in the accusative case than they do in the dative case:
Whilst you might hear some other contractions in spoken German (i.e. "aufs", "durchs", "fürs", "übers", "ums", "unters", they are quite colloquial and you should use the uncontracted forms in formal writing.
