“Proper” English is full of stumbling blocks, and chief among them is the sentence that ends in a preposition. For example, this question: Are sentences that end in prepositions really something to be ...
If dual-case prepositions describe movement from one place to another, they are followed by the accusative case. Otherwise, they take the dative. Ich stecke die Schuhe unter das Bett. – I put the ...