Learn Hardcore Russian: Мы сидим в кругу в парке.

So сидим alone expresses “(we) are sitting”; you do not add anything like есть here. Using есть in this kind of sentence would be wrong or sound very strange.

Does сидим mean “sit” or “are sitting”? How do Russians hear it?

The verb сидим (from сидеть) is imperfective present tense, 1st person plural:

It can mean “we sit” (a regular action)
- Каждый день после школы мы сидим в парке. – We sit in the park every day after school.
Or “we are sitting” (right now)
- Смотри, мы сидим в кругу в парке. – Look, we are sitting in a circle in the park.

Russian does not have a separate continuous form like English am/are sitting. Context tells you whether it’s a habitual action or happening now.

Why is it в кругу and not в круге?

Both в кругу and в круге are grammatically possible, but they are used differently:

в кругу is an idiomatic “second locative” form and is the normal choice in set expressions like:
- в кругу друзей – in the circle of friends / among friends
- в кругу семьи – in the family circle / with the family
In Мы сидим в кругу в парке, в кругу means “in a circle (of people), surrounded by them” and sounds natural and idiomatic.
в круге is more literal, like “inside a (drawn / geometric) circle”, and is much less common in everyday speech.

So here в кругу is used because it means “in a (social) circle”, not “inside a drawn shape”.

What exactly does в кругу mean here – physically in a ring, or “among people”?

In this sentence it suggests both:

physically: people are sitting arranged in a circle (for example, facing each other)
socially: they are within a group, “in the circle” of those people

In Russian, сидеть в кругу usually implies a group of people sitting in a round formation, often with a connotation of being together / in a cozy or friendly group. It’s not just “in a park” somewhere; it highlights the circular arrangement.

Why do both кругу and парке use в? Is that normal?

Yes, it’s normal. You simply have two separate location phrases, each with its own в:

в кругу – in a circle (of people)
в парке – in the park

So the sentence structure is:

Мы сидим [в кругу] [в парке].

Each в governs its own noun phrase. Using в twice like this is very common in Russian; there is no rule that you must “share” one preposition for both phrases.

Why is it в парке, not на парке? What’s the difference?

For парк (park), the usual preposition for location is в:

в парке – in the park (inside its territory)

на парке is wrong for this meaning.

The general (but not absolute) tendency is:

в
- place = inside an enclosed or bounded space:
  - в доме (in the house), в городе (in the city), в парке (in the park)
на
- place = on a surface, or open area, or some institutions/events:
  - на улице (on the street), на площади (on the square), на стадионе (at the stadium), на концерте (at the concert)

So в парке is the natural way to say “in the park”.

Which grammatical cases are кругу and парке?

Both are forms of the prepositional (locative) case used after в to show location, but кругу is a special variant:

кругу – a special locative form (often called “second locative”) of круг
Used mainly with certain prepositions (в, на) in fixed expressions:
- в кругу друзей, в кругу семьи, в снегу, в лесу.
парке – regular prepositional case of парк
- в парке, о парке (about the park)

So grammatically they function the same here (location after в), but кругу has this special -у ending because the phrase в кругу is idiomatic.

Is the pronoun Мы necessary? Could you just say Сидим в кругу в парке?

You can drop Мы:

Сидим в кругу в парке.

This is understandable and can appear in informal speech or written narrative, especially when the subject is already clear from context.

However:

Including Мы is the neutral, full sentence and is safest for learners.
Omitting it gives a slightly colloquial / narrative feel, as if someone is describing what “we” are doing in the moment.

So Мы сидим в кругу в парке is the standard form; Сидим в кругу в парке is possible but more context‑dependent.

Can the word order change, like В парке мы сидим в кругу?

Yes. Russian word order is more flexible than English. All of these are possible:

Мы сидим в кругу в парке. – neutral, straightforward.
Мы в парке сидим в кругу. – slight emphasis on “(not elsewhere,) in the park we sit in a circle.”
В парке мы сидим в кругу. – emphasizes “in the park” as the setting.
В кругу мы сидим в парке. – unusual; would sound odd or need special context.

The most natural everyday version is the original:
Мы сидим в кругу в парке.

How would the sentence change in past or future tense?

Verb сидим changes; everything else stays the same:

Present:
- Мы сидим в кругу в парке. – We are sitting / We sit in a circle in the park.
Past (masc. group or mixed group):
- Мы сидели в кругу в парке. – We were sitting / We sat in a circle in the park.
Future:
Analytic future of сидеть (imperfective):
- Мы будем сидеть в кругу в парке. – We will be sitting / will sit in a circle in the park.

How do you pronounce the sentence and where is the stress?

Stress marks (capital letters show stressed vowels):

Мы сидИ́м в кругУ́ в пА́рке.

Details:

мы – [мы], unstressed ы
сидим – si‑DÍM, stress on -дим
в кругу – [ф круу́], в often pronounced like [ф] before к, stress on -гу́
в парке – [ф пА́рке], stress on пА́р-

Spoken smoothly, it sounds like:
Мы сидИм ф кругУ ф пАрке.

Can you say Мы сидим кругом в парке instead of в кругу?

No, that would be wrong or mean something else.

кругом usually means:
- “around, all around” – Вокруг нас кругом лес. – There is forest all around us.
- “completely, entirely” in some contexts.
- “wrong / mistaken” in colloquial phrases: Ты всё делаешь кругом неправильно.

It does not mean “in a circle (as a formation of people)”.

To say that people are sitting arranged in a circle, you should use:

Мы сидим в кругу в парке.
or
Мы сидим кругом – only in some dialectal/colloquial uses; for learners в кругу is the correct, standard form.