Learn Icelandic: Stekkur hundurinn yfir okkur?

The preposition yfir (over) takes the accusative case when it describes motion or direction across a path to a destination. Because the dog is actively moving by jumping over us, it takes the accusative. If the dog were just resting or hanging in the air above us without changing location, it would take the dative case.

Wait, is okkur the accusative form? I thought it was the dative form for "us".

It is both! For the pronoun við (we), the accusative and dative forms are identical: okkur. So while the motion of jumping dictates that this is grammatically the accusative case, the word looks exactly the same as it would in the dative.

What is the infinitive (dictionary form) of the verb stekkur?

The infinitive is stökkva (to jump). This verb has a vowel shift in the present tense, changing the ö to an e to become stekkur (jumps) for the he/she/it form.

Why is the verb stekkur at the very beginning of the sentence?

To form a yes/no question in Icelandic, you simply move the verb to the front of the sentence. English usually adds a helper word like "does" or "do" (Does the dog jump?), but Icelandic just swaps the verb and the subject: hundurinn stekkur (the dog jumps) becomes stekkur hundurinn? (does the dog jump?).