Learn Hardcore Russian: Дети смеются, потому что мама купила им сок вместо того чтобы снова брать газировку. - The children are laughing because Mom bought them juice instead of getting soda again.

Дети смеются literally is “Children laugh”, but in context it corresponds to “The children are laughing.”
The present-tense form смеются already includes the meaning “are …-ing”.

So:

они смеются = they are laughing / they laugh
Russian simply doesn’t need “are” here.

Why is смеются and not смеют or something else? What is that -ются ending?

Смеются is:

3rd person plural
present tense
of the verb смеяться (to laugh), which is reflexive.

Structure:

сме- – verb stem
-ют – 3rd person plural ending (они смеют / поют / живут…)
-ся → in spelling -ться / -ться (here it becomes -ются because of spelling and pronunciation rules)

So:

он смеётся – he is laughing
они смеются – they are laughing

The reflexive ending -ся / -сь is built into the form; you never say смеют to mean laugh. Смеют exists but from a different verb сметь (to dare).

Why is there a comma before потому что?

Потому что introduces a subordinate because-clause, so Russian punctuation normally requires a comma between the main clause and the потому что-clause.

Дети смеются, потому что мама купила…
- Main clause: Дети смеются
- Subordinate clause: потому что мама купила им сок…

In Russian, almost every “because” (= потому что) clause will be separated by a comma, just like:

Я ушёл, потому что был устал. – I left because I was tired.

Is there any difference between потому что and так как here?

Both mean “because”, but they differ slightly in style and emphasis.

потому что – the most neutral, everyday “because”; works perfectly here.
так как – a bit more formal or explanatory, often used in written or more official speech.

You could say:

Дети смеются, так как мама купила им сок…

It would still be correct, just slightly more formal or “textbook-like.”

Why is it мама купила, not мама купил? Does the verb agree with gender?

Yes. In the past tense, Russian verbs agree in gender and number with the subject.

мама купила – subject мама is feminine → verb takes feminine form купила
masculine: папа купил – dad bought
neuter: молоко скисло – the milk has gone sour
plural: родители купили – the parents bought

So:

мама купила сок – Mom bought juice. (feminine past)

What does купила им сок literally mean? Why им and not something else?

Купить can mean “to buy something for someone” when you add a dative pronoun.

купила сок – she bought juice (no mention for whom)
купила им сок – she bought them juice / she bought juice for them

Им is the dative plural of они:

они – they (nominative)
им – to them / for them (dative)

So купила им сок = bought (for) them juice.

Why is it сок and not сока after купила?

After a transitive verb in a normal affirmative sentence, the direct object is usually in the accusative case:

купила сок – bought (some) juice
- сок is accusative singular (same form as nominative for masculine inanimate nouns).

Сока is genitive. You would use сока when:

You talk about an unspecified amount or absence:
- нет сока – there is no juice
- немного сока – a bit of juice

But in купила сок, she just bought juice, standard direct object → accusative сок, not сока.

Why is it вместо того чтобы, and what is happening grammatically with того?

Вместо того чтобы + infinitive is a fixed construction meaning “instead of doing something.”

вместо – instead of (a preposition that takes genitive)
то – that/it
того – genitive of то (because вместо requires genitive)
чтобы – conjunction introducing the action you’re contrasting
брать газировку – the action

So:

вместо того чтобы снова брать газировку
= instead of taking soda again

Think of it as a bundle: вместо того чтобы + infinitive = instead of doing X.

Grammatically, того is in the genitive because of вместо.

Should there be a comma in вместо того чтобы, like вместо того, чтобы?

In careful, standard written Russian, a comma is normally placed:

вместо того, чтобы снова брать газировку

Many native speakers omit it in informal writing, as in your sentence, but most style guides recommend the comma here because того and чтобы function together as a correlative “instead of that, in order to…” structure.

So:

With comma – more correct/formal: вместо того, чтобы…
Without comma – common in informal text, but less standard.

Why is the verb брать used (to take), not пить (to drink) or взять (to take once)?

Here брать газировку means something like “to choose / get / take soda (from the store, fridge, menu)”.

Aspect:

брать – imperfective, focuses on a repeated or general action:
- брать газировку – to (habitually) take soda, to be the sort of person who grabs soda.
взять – perfective, one-time completed action:
- взять газировку – to take soda (once).

Because the idea is “instead of (again) getting soda as usual”, the imperfective брать fits better.

If you said пить газировку, you would shift the meaning to “instead of drinking soda again”, focusing on drinking, not choosing/buying. That would also be grammatically fine, just a slightly different nuance.

Why is газировку in that form and not газировка?

Газировка (soda) is a feminine noun. In брать газировку, it is a direct object in the accusative case:

nominative: газировка – soda (as subject)
accusative: газировку – soda (as direct object)

So:

Газировка полезна? – Is soda healthy? (nominative)
Он часто берёт газировку. – He often gets soda. (accusative)

Hence брать газировку, not брать газировка.

Could I say вместо того чтобы снова пить газировку instead? Would it still be correct?

Yes, that is fully correct and natural; it just slightly changes the focus:

снова брать газировку – to (again) take/get soda (e.g., at the store, when ordering)
снова пить газировку – to (again) drink soda

Both make sense:

вместо того чтобы снова брать газировку – Mom changed what she chooses to buy/take.
вместо того чтобы снова пить газировку – Mom changed what they drink.

The original sentence highlights the choice of drink (buying/taking) rather than the physical act of drinking.

Could I replace вместо того чтобы снова брать газировку with а не газировку? For example: мама купила им сок, а не газировку.

Yes, you can, but the structure and nuance change a bit.

мама купила им сок вместо того чтобы снова брать газировку
– contrasts two actions: buying juice vs (again) taking soda.
мама купила им сок, а не газировку
– contrasts two objects of the same action: she bought juice, not soda.

Both convey essentially the same idea in this context, but:

вместо того чтобы… emphasizes the alternative action.
а не газировку emphasizes what exactly was bought.

Could the word order be Смеются дети, потому что… or Мама им купила сок? Does that change the meaning?

Russian word order is more flexible than English and often changes emphasis, not basic meaning.

All of these are grammatically correct:

Дети смеются, потому что мама купила им сок… – neutral order.
Смеются дети, потому что мама купила им сок… – puts emotional or stylistic emphasis on смеются (the laughing).
Мама им купила сок – emphasizes им (to them), somewhat like “Mom bought them juice (for them in particular).”
Мама купила им сок – still mentions им, but more neutral.

So yes, you can change the order, but you’re also slightly shifting what is highlighted in the sentence.