in, auf, an…: the nine that take two cases depending on wo or wohin
CEFR A2 · part 2
edumaterial's parts within the level. The European framework does not subdivide them.
weil and dass: the clause where the verb goes to the endJoining two clauses with weil, dass, wenn or ob and sending the conjugated verb to the…The adjective in front of the noun: when -e and when -enGiving the adjective an ending when it sits in front of the noun, with the short rule…war, hatte, konnte: the past tense people do say out loudUsing in the past the eight verbs a German never puts into the Perfekt when speaking…The imperative and German's three «you»: du, ihr, SieGiving an instruction to the three people German lets you address, and knowing which is…Comparing in German: -er, als, and am -stenComparing two things and pointing out the top one, with German's three pieces: the -er…mich or mir, dich or dir: pronouns in the accusative and dativeReplacing anything already mentioned with a pronoun, in both cases, and placing it…The rule, in three lines
Nine prepositions take both cases and choose with a single question: in, an, auf, über, unter, vor, hinter, neben, zwischen. If the sentence answers WOHIN —where to, there is movement towards that place— it is accusative: Ich gehe in die Küche. If it answers WO —where, nothing leaves its place— it is dative: Ich bin in der Küche. And from that come the contractions: in das = ins, in dem = im, an das = ans, an dem = am.
The usual slip. Deciding by the verb instead of by the question. It is not that gehen takes the accusative and sein the dative: Ich tanze im Zimmer is dancing inside the room and Ich tanze ins Zimmer is dancing your way into it. Same verb, two cases, two scenes. The deciding question is always wo or wohin, and you put it to the whole sentence, not to the verb.
Why it catches you out. English does have the distinction —«into the room» against «in the room»— and that is the best model of the four: into is the accusative and in is the dative. Where English gives no help is auf and an, because it uses «on» and «at» for both movement and place without changing anything.