Learn Hardcore Russian: На спортплощадке у школы всегда есть кто‑то, с кем можно поиграть в баскетбол. - At the sports ground by the school there is always someone with whom you can play basketball for a while.

A спортплощадка is an open sports ground, not something you are inside like a building, so Russian sees it as a surface/area: на спортплощадке.

If you were talking about being inside a building, you’d use в:

в школе – in/at school
в спортзале – in the gym

What does у школы literally mean, and why is it школы?

The preposition у with the genitive case usually means:

by / near / next to a place, or
at someone’s place (у мамы, у друга, у бабушки)

So у школы literally means “by the school” or “next to the school”.

Школы is the genitive singular of школа:

nominative (dictionary form): школа
genitive: школы

Compare:

в школе – in/at school (inside)
у школы – by/near the school (outside, nearby)

Which case is спортплощадке, and how can I recognize it?

Спортплощадке is in the prepositional case singular (feminine).

You see it after на (with a location meaning), and the ending -е is typical for feminine nouns ending in -а:

nominative: спортплощадка
prepositional (where?): на спортплощадке

Other examples:

на работе (from работа)
на кухне (from кухня)
в школе (from школа)

So: на + (fem. -а) → usually -е in the prepositional case.

Why do we need есть here? Could we say На спортплощадке у школы всегда кто‑то, с кем можно поиграть…?

Here есть is the verb that creates an existential sentence: “there is / there exists”.

Pattern:

[Где?] + есть + [кто/что?]
- На спортплощадке у школы всегда есть кто‑то…
- В комнате есть стол. – There is a table in the room.

If you remove есть, the sentence is still understandable, but it sounds incomplete or informal here. In standard, neutral speech, in this structure with всегда, Russians normally keep есть.

You can omit есть more easily when something is permanent, obvious, or a characteristic:

Стол в комнате. – (The) table is in the room.
Он дома. – He is at home.

But for “there is always someone”, есть is the natural, normal choice.

What is the difference between кто‑то and кто‑нибудь? Could I use кто‑нибудь here?

Both mean “someone”, but the nuance is different:

кто‑то – some specific but unknown person; the speaker is sure that such a person exists.
- “someone (definite for the speaker, just unnamed)”
кто‑нибудь – “anyone at all”, often with more uncertainty or “it doesn’t matter who”; typically used in:
- questions: Здесь есть кто‑нибудь? – Is anyone here?
- negatives: Здесь нет кого‑нибудь. – There isn’t anyone.
- conditionals: Если придёт кто‑нибудь… – If anyone comes…

In this sentence, the idea is “there is always someone (for sure) to play with”, so кто‑то is perfect.
Кто‑нибудь would weaken that feeling of certainty and sound less natural here.

Why is there a hyphen in кто‑то?

Russian indefinite pronouns are often formed with little particles that attach with a hyphen:

кто‑то – someone
что‑то – something
где‑то – somewhere
когда‑то – sometime

The same with other particles:

кто‑нибудь
что‑нибудь
кто‑либо, что‑либо

So the hyphen is simply part of the standard spelling: pronoun (кто) + particle (то) = кто‑то.

What does с кем mean grammatically? Why кем, not кто?

С кем literally means “with whom”.

The pronoun кто (“who”) changes its form by case. Кем is its instrumental case, and the preposition с (“with”) requires the instrumental when it means “together with someone”.

Declension of кто:

Nominative (who?): кто
Genitive (of whom?): кого
Dative (to whom?): кому
Accusative (whom?): кого
Instrumental (with whom?): кем
Prepositional (about whom?): ком

So:

с кем можно поиграть – with whom one can play
с другом – with a friend
с мамой – with (my) mom

All of these use the instrumental case after с.

Why is it можно поиграть, not just можно играть? What nuance does поиграть add?

Играть and поиграть are different aspects of the same verb:

играть – imperfective: process, ongoing/habitual activity (“to play” in general).
поиграть – perfective: a complete action, usually “to play for a while / for some time”.

In с кем можно поиграть в баскетбол the idea is:

there is someone you can (actually) play a game with, i.e., you could go and have a game of basketball now or at some specific time.

If you said с кем можно играть в баскетбол, it would sound more like:

“someone with whom one (generally) can play basketball (as an activity in life)”, a more general or habitual statement.

Both are possible grammatically, but поиграть matches the natural meaning here: a concrete, bounded action (“have a game”).

In с кем можно поиграть, who is doing the playing? Why isn’t there a word for I/you/we?

The construction with можно + infinitive is impersonal in Russian. It means:

“it is possible to do X” / “one can do X” / “you can do X”

The doer is understood from context, not stated directly.

So:

с кем можно поиграть в баскетбол ≈ “with whom you can play basketball” / “with whom one can play basketball”.

Russian very often leaves out я / ты / мы in such modal, general statements:

Здесь можно курить. – One can / You can smoke here.
Тут нельзя парковаться. – You can’t park here.

Your English brain wants an explicit subject, but Russian doesn’t need one in this pattern.

Why do we say поиграть в баскетбол with в? Can we just say поиграть баскетбол?

With most games and sports, Russian uses the pattern:

играть / поиграть в + accusative

Examples:

играть в футбол – to play football
играть в теннис – to play tennis
играть в шахматы – to play chess
поиграть в баскетбол – to play (some) basketball

You cannot drop в here:
✗ поиграть баскетбол (incorrect in standard Russian)

Compare this with musical instruments, where Russian uses на + prepositional:

играть на гитаре – to play the guitar
играть на пианино – to play the piano

Another common verb for sports is заниматься:

заниматься баскетболом – to do/practise basketball (as an activity or hobby)

Is спортплощадка the same as спортивная площадка? Is there any difference?

Yes, спортплощадка is basically a shortened, more colloquial form of спортивная площадка.

спортивная площадка – literally “sports ground/court”, more formal/neutral.
спортплощадка – clipped compound, commonly used in everyday speech.

Meaning-wise in this context they are the same:

На спортивной площадке у школы…
На спортплощадке у школы…

Both mean the sports/playground area next to the school.

Can I move на спортплощадке у школы to a different place in the sentence? How flexible is the word order?

Russian word order is flexible, but some orders are more natural.

Your sentence is:

На спортплощадке у школы всегда есть кто‑то, с кем можно поиграть в баскетбол.

This follows a common existential pattern:

[Location] + (всегда) есть + [кто/что]…

You can move parts around, but the feel changes:

У школы на спортплощадке всегда есть кто‑то, с кем можно поиграть в баскетбол.
– Also natural; slightly more emphasis on у школы.
Всегда на спортплощадке у школы есть кто‑то, с кем можно поиграть в баскетбол.
– Puts more emphasis on всегда (“always, really always”).

If you split the location unnaturally, it can sound awkward:

✗ Есть кто‑то на спортплощадке у школы всегда, с кем можно поиграть… – grammatically possible but stylistically clumsy.

So yes, you can move the location phrase, but the original order is the most neutral and typical.