Learn Hardcore Russian: Утки подплывают к ребёнку за хлебом. - The ducks swim up to the child for bread.

Russian, like English, uses the plural when you are clearly talking about more than one duck. The sentence describes a general situation where several ducks are swimming up to the child for bread, so the subject is plural.

утка – one duck
утки – ducks (subject form, nominative plural)

If you wanted to speak about one duck, you would say:

Утка подплывает к ребёнку за хлебом.
A duck is swimming up to the child for bread.

What does подплывают mean exactly, and how is it different from плывут?

Both verbs are imperfective and describe a process:

плывут – they are swimming (no focus on destination)
подплывают – they are swimming up / approaching by swimming

The prefix под- often adds the idea of movement toward something / coming closer.

So:

Утки плывут. – The ducks are (just) swimming.
Утки подплывают к ребёнку. – The ducks are swimming up to / toward the child.

In the original sentence, the fact that they are approaching the child (not just swimming somewhere) is important, so подплывают is used.

Is подплывают present tense, and what aspect is it?

Yes, подплывают is present tense, imperfective aspect.

Imperfective: focuses on the process, repeated action, or ongoing nature
Perfective counterpart: подплыть – to swim up (as a completed event)

Examples:

Утки подплывают к ребёнку за хлебом.
The ducks are (in general / right now) swimming up to the child for bread.
Утки подплывут к ребёнку за хлебом.
The ducks will swim up to the child for bread (once, as a completed event in the future).

Why is it к ребёнку and not к ребёнок?

Because к requires the dative case to show direction toward someone or something.

к
- dative = towards / to (a person or object)

Ребёнок is nominative (dictionary form).
In the dative singular, it becomes ребёнку:

nominative: ребёнок – child
dative: ребёнку – to the child, toward the child

So:

к ребёнку – toward the child
к маме – toward (to) mom
к дому – toward the house

What exactly does the preposition к mean here? Is it like "to"?

Yes, к is similar to English to / toward, but with a nuance of direction toward a point, often a person.

With a person or a place, к + dative typically means:

Movement toward someone/something (often up to them)
Sometimes visiting someone

Examples:

Идти к врачу. – To go to the doctor.
Подойти к окну. – To walk up to the window.
Подплывать к ребёнку. – To swim up to the child.

In your sentence, к ребёнку is toward the child – the ducks are approaching the child.

Why is it за хлебом and not за хлеб?

Because за can take instrumental or accusative, with different meanings:

за
- accusative → usually behind / beyond / for (in exchange for)
за
- instrumental → often for, after, in search of, to get something

In your sentence we have за хлебом (instrumental):

за хлебом – for bread / to get bread / in search of bread

This is a common pattern for going to obtain something:

пойти за хлебом – to go (out) for bread
пойти за молоком – to go for milk
зайти за другом – to go pick up a friend

So подплывают к ребёнку за хлебом literally is swim up to the child for bread / to get bread from the child.

What case is хлебом, and why is that case used?

Хлебом is instrumental singular of хлеб.

Reason: the preposition за often takes the instrumental case with the meaning for / in search of / to get something.

Compare:

за столом – at the table (location; also instrumental)
идти за хлебом – go for bread (purpose; instrumental)

So with за хлебом the instrumental case shows the object being sought / obtained.

What is the difference between за хлебом and something like для хлеба?

They are not interchangeable:

за хлебом (instrumental) – for bread in the sense of to get bread / after bread
- Утки подплывают к ребёнку за хлебом.
  The ducks swim up to the child for bread (to get bread).
для хлеба (genitive) – for bread in the sense of intended for bread / for use with bread
- Корзина для хлеба. – A basket for bread (intended to hold bread).
- Нож для хлеба. – A knife for bread (a bread knife).

So in your sentence, the idea is purpose of movement (to get bread), so за хлебом is correct; для хлеба would be wrong there.

Could we say за хлеб instead of за хлебом here?

Not in this meaning.

за хлебом (instrumental) – for bread / to get bread (correct in your sentence)
за хлеб (accusative) would typically be used in different contexts:
- бороться за хлеб – to fight for bread (metaphorically: for livelihood)
- платить за хлеб – to pay for bread (in exchange for)

For movement with the meaning go in order to obtain something, Russian strongly prefers за + instrumental:

идти за хлебом / за молоком / за ребёнком (to go get the child)

So: подплывают к ребёнку за хлебом is the correct form.

Is there any article implied, like "the ducks", "the child", "the bread"?

Russian has no articles at all, so words like утки, ребёнок, хлеб do not show a / an / the on their own.

Whether you translate it as the ducks or ducks depends on context in English. In this typical everyday situation, a natural translation would be:

The ducks are swimming up to the child for bread.

But grammatically, the Russian sentence itself does not specify definiteness; it’s neutral in that sense.

Can we change the word order, for example: Утки за хлебом подплывают к ребёнку?

Yes, Russian word order is relatively flexible, and that version is grammatically correct.

Different orders add slight nuances or emphasis:

Утки подплывают к ребёнку за хлебом.
Neutral: ducks → are swimming up → to the child → for bread.
Утки за хлебом подплывают к ребёнку.
Emphasizes за хлебом a bit more: it highlights that the ducks’ purpose is bread.

All of these would be acceptable in normal speech:

Утки подплывают за хлебом к ребёнку.
К ребёнку подплывают утки за хлебом.

Intonation will then help signal what is emphasized.

What does ребёнок mean exactly? Is it like "boy", "girl", or just "child"?

Ребёнок means child (a young human being), and it is gender-neutral in meaning.

biologically: could be a boy or a girl
grammatically: it is masculine noun in Russian

Some related forms:

ребёнок – a child (singular)
дети – children (plural; irregular)
к ребёнку – to the child (dative singular)

If you wanted to specify gender, you’d use мальчик (boy) or девочка (girl), but ребёнок is neutral.

How would the sentence change in the past and future tenses?

Same structure, but the verb changes:

Present (imperfective):
Утки подплывают к ребёнку за хлебом.
The ducks (are) swim(ming) up to the child for bread. (habitual / right now)
Past (imperfective):
Утки подплывали к ребёнку за хлебом.
The ducks were swimming up / used to swim up to the child for bread.
Future (perfective):
Утки подплывут к ребёнку за хлебом.
The ducks will (swim up and) reach the child for bread (a completed future event).