Questions & Answers about Мы сидели вокруг костра.
Why is the word for campfire in the genitive case (костра) here?
The preposition вокруг (around) always requires the noun that follows it to be in the genitive case. Because the dictionary form костёр (campfire) is a masculine noun, it takes the -а ending in the genitive.
The dictionary word for campfire is костёр. Where did the ё go in костра?
Костёр has what is called a "fleeting vowel." In Russian, certain masculine nouns drop their last vowel (often о, е, or ё) when a case ending is added. Because of this rule, костёр becomes костра, rather than having the awkward spelling of костёра.
Why is the imperfective verb сидели used here instead of a perfective form?
Sitting around a campfire is an ongoing state or a continuous action in the past, rather than a completed, one-time event with a result. Whenever you are describing a prolonged state like "we were sitting," the imperfective aspect is the correct choice.
Could I use около instead of вокруг to mean "around"?
Not exactly. While около also takes the genitive case, it translates to "near" or "by." Saying около костра just means you sat close to the fire. Вокруг specifically means you were arranged in a circle surrounding it.