Learn Polish: Pies zbiegł wczoraj ze schodów. - The dog ran down the stairs yesterday.

Adding the prefix z- to a motion verb usually indicates a downward motion. Here, biec (to run) becomes zbiec (to run down). It also makes the verb perfective, meaning the action is entirely completed—the dog finished its run to the bottom of the stairs.

Why does the sentence use ze instead of z before schodów?

We use ze instead of z purely to make pronunciation easier. Since schodów starts with the consonant cluster sch- (which begins with an s sound, very similar to z), saying z schodów would be quite a tongue twister! Adding the -e breaks up these tricky consonants.

Why is schodów in the Genitive case here?

The preposition z or ze always requires the Genitive case when it means "down from" or "out of." It is also worth remembering that schody (stairs) is a plural-only word in Polish, so schodów is specifically the Genitive plural form.

If the dog was in the process of running down the stairs yesterday, how would the verb change?