Learn Hardcore Polish: Dorośli pracują przy komputerach, a dzieci siedzą obok. - Adults are working at the computers, and children are sitting next to them.

i simply adds: Adults work and children sit (no contrast).
a contrasts or shifts the topic: Adults are working, whereas the children are sitting. In this sentence, a subtly highlights the difference between what the two groups are doing. A comma is normally placed before a.

Why is it przy komputerach instead of na komputerach or przed komputerami?

przy komputerach = at/by the computers (physically positioned at a workstation; often suggests being seated there and using them).
na komputerach = on computers (idiomatic for using computers as a tool/platform: pracować na komputerze is common and correct).
przed komputerami = in front of the computers (focuses on physical position in front of screens, not necessarily using them). All three can be correct depending on the emphasis. Here, przy stresses the adults are stationed at the computers.

What case is komputerach, and why?

It’s locative plural. The preposition przy always governs the locative case.

Singular: przy komputerze
Plural: przy komputerach Base noun: komputer → locative plural ending -ach.

Why is the plural dzieci used for children, and how does it affect agreement?

Singular: dziecko (neuter). Plural: dzieci (irregular).
dzieci is a non-masculine-personal plural, so adjectives and past-tense verbs take non-masculine-personal forms:
- Present: Dzieci są małe.
- Past: Dzieci siedziały (not: siedzieli). Compare with masculine-personal plural dorośli:
- Dorośli są zmęczeni.
- Dorośli pracowali.

Is Dorośli a noun here? How would I say “adult women only”?

Yes. Dorośli is originally an adjective (from dorosły) used as a noun meaning adults (masculine-personal plural; typically mixed-gender or at least one man).

Forms of the adjective: dorosły (m sg), dorosła (f sg), dorośli (m-personal pl), dorosłe (non-masc-personal pl). For only women, say e.g. dorosłe kobiety or dorosłe osoby. Bare dorosłe as “adults” is uncommon unless the context is crystal-clear.

Could I say dorośli pracują z komputerami?

You can, but the meaning shifts:

pracować z komputerami = work with computers (computers are involved in their job in general).
pracować przy komputerach = be at computer stations (describes the physical setup).
pracować na komputerach = work on computers (use them as a tool). Choose based on what you want to emphasize.

What exactly does obok mean here? Does it need something after it?

obok = next to/beside/nearby.

As used in the sentence, it’s an adverb: dzieci siedzą obok = the children are sitting next to (someone/something understood from context).
As a preposition, it takes the genitive: obok dorosłych (next to the adults), obok komputerów (next to the computers), obok nich (next to them).

Why is there a comma before a?

Polish punctuation places a comma before the contrasting coordinator a. With i (simple and), you normally do not use a comma between two main clauses unless there’s another reason (e.g., parentheticals).

Can I change the word order?

Yes. Polish word order is flexible, and you can shift elements for emphasis:

Przy komputerach pracują dorośli, a obok siedzą dzieci. (fronts locations for contrast)
Dzieci obok siedzą. (emphasis on obok)
Dorośli przy komputerach pracują, a dzieci siedzą obok. (focus on the locations) All are grammatical; the default order is neutral and clear.

What tense/aspect are pracują and siedzą? Is it “are working” or “work”?

They’re present tense, imperfective. Polish imperfective present can match English simple or progressive:

“Adults work at computers” (habitual)
“Adults are working at computers” (right now) Context decides which English translation fits.

What’s the difference between siedzą, siadają, and usiądą/usiąść?

siedzą (from siedzieć) = they are sitting (state).
siadają (from siadać, imperfective) = they sit down / they are taking a seat (process, repeated or ongoing).
usiądą (from perfective usiąść) = they will sit down (single, completed action in the future). Imperative: usiądźcie!

How do you pronounce tricky parts like przy, Dorośli, pracują, siedzą?

rz (as in przy) sounds like zh in “measure”; przy ≈ “pshih/pshɨ”.
ś (as in Dorośli) is a soft sh; Dorośli ≈ “do-RO-shlee” (with a very soft sh).
Final -ą (nasal o) in pracują, siedzą is nasalized, often close to “-on” in casual speech: pracują ≈ “pra-TSOO-yon”, siedzą ≈ “SHED-zon”. Don’t worry about being perfect with nasal vowels at first; clear segment timing matters more.

Why plural komputerach? Could I use singular komputerze?

Use plural if there are multiple computers: przy komputerach. If there’s only one, say przy komputerze (locative singular).

How do I explicitly say “next to them” at the end?

Add a genitive pronoun after obok:

Dorośli pracują przy komputerach, a dzieci siedzą obok nich. (…next to them.)

Can I use przy with people, e.g., “the children are sitting by the adults”?

Yes, but the nuance differs:

Dzieci siedzą przy dorosłych. suggests by/at the side of the adults (e.g., sharing a table).
Dzieci siedzą obok dorosłych. is a neutral “next to” without implying a shared place or participation.

Why is it siedzą and not something like siedzią? How is it conjugated?

The verb is siedzieć (to sit). Present tense:

ja siedzę
ty siedzisz
on/ona/ono siedzi
my siedzimy
wy siedzicie
oni/one siedzą So third-person plural ends with -ą: siedzą.