Where To? Accusative vs Locative

After у and на, Serbian uses two different cases, and the verb decides which one.

• Movement to a place (куда? – where to?) takes the accusative: Идем у школу. (I'm going to school.) Путујем у Грчку.
• Being in a place (где? – where?) takes the locative: Деца су у школи. (The children are at school.) Живе у Грчкој.

Verbs like ићи, путовати, улазити, носити point to the accusative; бити, живети, радити, спавати point to the locative.

Masculine nouns for things and all neuter nouns look unchanged in the accusative, so only the locative shows a new ending: Идемо на море, but Сада смо на мору. Идем на посао, but Мама је на послу.