Learn Hardcore Chinese: háizi cóng xuéxiào huílái de shíhou chángcháng hěn è, māma huì mǎshàng zuò wǎnfàn gěi tāmen chī. - When the kids come back from school they’re often very hungry, and mom immediately makes dinner for them.

You need 的 because “回来的时候” is a verb phrase (回来) modifying the noun 时候. In Chinese, when a verb/verb phrase modifies a noun (like an English relative clause), it usually needs 的:

我回来的时候 = when I come back / when I came back
他下班的时候 = when he gets off work

Saying 回来时候 without 的 is ungrammatical in standard Mandarin. Think of 的 here as turning 回来 into an “adjective/relative clause” to describe 时候.

What exactly does 从学校回来 mean? Where is “home”? Why not 回家?

从学校回来 literally means “come back from school.” In real-life context, it almost always implies “come back home” if that's the usual destination.

从学校回来 – focuses on the starting point: “from school (come back)”
回家 – explicitly says the destination: “go/come home”

You could also say:

孩子从学校回家以后常常很饿 – “After the kids come home from school, they’re often hungry.”

The original sentence omits 家, but native speakers easily infer “home” from context. It’s natural and common.

What is the function of 的时候 here? Is it just “when”? Could we just say 孩子从学校回来常常很饿?

的时候 means “when / at the time (that).” The structure is:

[Clause] + 的时候 + [Main situation]
孩子从学校回来的时候，常常很饿。
When the children come back from school, they are often hungry.

If you say 孩子从学校回来常常很饿, it sounds incomplete/unnatural, because 回来 is an action, and you need 的时候 (or something similar like 以后) to turn it into a time phrase:

孩子从学校回来以后常常很饿 – also natural: “After the kids come back from school, they’re often hungry.”
孩子从学校回来的时候常常很饿 – “When the kids come back from school, they’re often hungry.”

So 的时候 marks a time frame based on that clause.

Why doesn’t this sentence use 在 like 在……的时候? Is 在孩子从学校回来的时候 better?

Both are correct:

孩子从学校回来的时候常常很饿。
在孩子从学校回来的时候，孩子常常很饿。

在 … 的时候 is a bit more explicit and sometimes a bit more formal/emphatic. Omitting 在 is extremely common and usually more natural in ordinary speech and writing.

So you don’t need 在 here. Adding it is optional, not required.

Does 会 in 妈妈会马上做晚饭给她们吃 mean “can,” “will,” or “would”? Why is it used?

Here 会 is not “can (ability)” but “will / tends to / is likely to (do something).”

In this context, 会 often expresses:

habitual tendency
predictable response in that situation

So:

妈妈会马上做晚饭给她们吃。
≈ “The mother will (tends to / usually will) immediately make dinner for them to eat.”

Compare:

妈妈马上做晚饭给她们吃。 – more like a simple statement of what happens; feels a little more like a narration.
妈妈会马上做晚饭给她们吃。 – suggests “this is what she typically/usually does in that situation.”

It’s similar to English “When X happens, Mom will (typically) do Y.”

Why is 给她们吃 at the end? What does 给 do here, and why do we need 吃?

The structure is:

做晚饭给她们吃
literally: “make dinner, give them eat”

Breakdown:

给 here means “for / to (someone)” – it marks the recipient/beneficiary.
吃 is the verbal action “eat.”

So 给她们吃 is “for them to eat.” The whole phrase means:

“(She) makes dinner for them to eat.”

You generally cannot stop at 给她们 here, because that just means “give them (something)” and leaves the verb 吃 implied or missing. In spoken Chinese, if it’s super obvious, sometimes 吃 can be dropped in context, but in a full sentence like this, 给她们吃 is the natural complete pattern.

Could we say 给她们做晚饭 instead of 做晚饭给她们吃? Is the meaning different?

Yes, both are correct; the emphasis is slightly different in word order:

给她们做晚饭
- literally: “for them make dinner”
- structure: 给 + recipient + 做 + thing
- more emphasis on for whom you are doing it.
做晚饭给她们吃
- literally: “make dinner for them to eat”
- structure: 做 + thing + 给 + recipient + 吃
- emphasizes the action “make dinner,” and 给她们吃 describes the purpose/recipient.

Both are natural. In your sentence, 做晚饭给她们吃 nicely foregrounds the 做晚饭 action as the response to their hunger.

Why is it 她们 and not 他们? Does this mean the children are all girls?

Yes. In writing:

他们 – “they / them (mixed group or all males)”
她们 – “they / them (all females)”

Using 她们 implies the children are all girls. If the group were mixed (boys and girls) or just unspecified, writers usually use 他们.

Important: in spoken Mandarin, 他们 and 她们 are pronounced the same: tāmen. The difference only appears in characters/writing.

Does 很饿 here mean “very hungry”? Why is 很 needed?

很饿 can mean “very hungry,” but in many everyday sentences 很 is more like a neutral linker between the subject and an adjective, often not strongly “very.”

In Chinese, adjectives often function like stative verbs. If you just say:

她们饿。

it can sound abrupt or like a contrast (“They ARE hungry (as opposed to what you think)”) or a simple predicate in certain contexts, but it’s less natural as a generic description.

Adding 很:

她们很饿。

usually just means “They are hungry” in neutral, descriptive way. Whether it feels like “very” or just “quite / really / (plain) are” depends on context and tone.

So 常常很饿 is best understood as “often (really) hungry,” which in smooth English is just “often hungry.” The 很 makes the sentence sound natural and less abrupt.

What’s the difference between 常常 and 经常 here? Could we say 经常 instead?

Both 常常 and 经常 mean “often / frequently.” In many contexts, they are interchangeable:

孩子从学校回来的时候经常很饿。 – also correct.

Subtle differences (not strict rules):

经常 can sound slightly more formal or written in some regions.
常常 can feel a bit more colloquial in some contexts.

But in this sentence, either is fine. Native speakers use both.

Why is 马上 placed before 做晚饭? Could it go somewhere else?

The usual word order is:

妈妈 + 会 + 马上 + 做晚饭 + 给她们吃。

马上 (“immediately / right away”) is an adverb that modifies the verb phrase 做晚饭. Typical position for such adverbs is before the main verb:

马上做 – immediately do (something)
常常吃 – often eat
已经看过了 – already have seen

Other positions:

妈妈马上会做晚饭给她们吃。 – grammatical, but this can be read as “Mom will soon (in the near future / right away) have the ability/will to make dinner,” which slightly shifts the focus to 会.
妈妈会做晚饭马上给她们吃。 – awkward; 马上 rarely goes after the main verb like this.

So 会马上做晚饭 is the most natural here: modal 会 + adverb 马上 + verb 做.

How do we know this sentence is talking about the past? There’s no 了 or past tense marker.

Chinese doesn’t require tense marking like English. Time is usually inferred from:

Context (story about daily routine, etc.)
Time expressions or aspect markers.

In this sentence, 从学校回来的时候常常很饿 describes a general habitual situation (whenever they come back from school) – it can refer to:

a present habit: “When they come back from school, they are often hungry.”
a past habit: “When they came back from school, they were often hungry.”

会 in 妈妈会马上做晚饭给她们吃 can be read as:

“will (typically) immediately make dinner for them” – present habit
“would immediately make dinner for them” – past habit, if context is clearly past.

So the time frame comes from narration context, not from a specific tense marker in this one sentence.

Why isn’t there a second 孩子 or 她们 before 常常很饿? How do we know who is hungry?

Chinese often avoids repeating subjects when they’re clear from context. The pattern here is:

孩子从学校回来的时候常常很饿
“When the kids come back from school, (they) are often hungry.”

Grammatically, the subject of 常常很饿 is still 孩子, carried over from the start of the sentence. Repeating it:

孩子从学校回来的时候，孩子常常很饿。

is redundant and sounds awkward unless you have a special reason for emphasis.

Chinese frequently uses this kind of “shared subject” across a clause + following predicate when it’s obvious who is being described.