Learn Hardcore Russian: Зачем‑то он ставит будильник на шесть утра, хотя в школу ему к восьми. - For some reason he sets his alarm for six in the morning, although he has to be at school by eight.

It means “for some (unknown / strange) reason”, “for who‑knows‑what purpose”.
It often implies the speaker thinks the action is pointless, odd, or at least unexplained.

So:

Зачем он ставит будильник на шесть утра? – Why does he set the alarm for six a.m.? (real question)
Зачем‑то он ставит будильник на шесть утра… – For some reason he sets the alarm for six a.m… (I don’t really see why; it seems unnecessary/strange.)

The particle ‑то is written with a hyphen and can attach to many pronouns and adverbs:
кто‑то, что‑то, где‑то, когда‑то, почему‑то, зачем‑то, etc., usually meaning “some / some kind of / for some reason”.

Why is it он ставит будильник, not something like он заводит будильник? Are both correct?

Both ставить будильник and заводить будильник exist, but they focus on different aspects and have slightly different typical uses.

Ставить / поставить будильник (на…)
- Very common, especially with an explicit time: ставить будильник на шесть утра.
- Emphasizes setting the alarm for a specific time.
- Literally “to place / set (the alarm) for six a.m.”
Заводить / завести будильник
- Historically: to wind a mechanical alarm clock.
- Now also used more generally as “to activate / switch on the alarm”.
- Can be used with or without a time phrase:
  - завести будильник на шесть – set/wind the alarm for six
  - завести будильник – just “set/turn on the alarm” (time may be clear from context).

In this sentence, ставит будильник на шесть утра is very natural because the time is given and the idea is “he sets it for six”. Заводит будильник на шесть утра would also be grammatical and understandable, just a bit less “default” sounding than ставит here.

Why is the verb ставит in the present tense? In English we would probably say “he sets” or “he keeps setting” as a habitual action. Is this the same idea?

Yes. Russian present tense of an imperfective verb (here ставить) often expresses habitual, repeated actions, just like English “he sets / he usually sets / he keeps setting”.

Он ставит будильник на шесть утра…
→ He (regularly) sets the alarm for six a.m… (this is his usual practice, not just one single time.)

If you said:

Он поставит будильник на шесть утра… (perfective, future)

that would normally mean one concrete future action: He will set the alarm for six a.m (on some particular occasion).

Here, the context sounds like we’re describing a habit, so the imperfective present ставит is exactly right.

Why is it на шесть утра and not в шесть утра? What does the preposition на do with time here?

The difference is tied to the type of verb and the idea of “target time” vs “time when something happens.”

на шесть утра after ставить будильник means:
→ “set it for six a.m.” (the target moment when the alarm should ring)
на is used with lots of verbs of planning/setting/scheduling to mean “for (a certain time)”:
- назначить встречу на три часа – schedule a meeting for three o’clock
- перенести урок на пятницу – move the lesson to Friday
- купить билеты на семь вечера – buy tickets for seven p.m.
Similarly: ставить будильник на шесть утра – set the alarm for six a.m.
в шесть утра usually means “at six a.m.”, describing when an action happens, e.g.:
- Будильник звонит в шесть утра. – The alarm rings at six a.m.
- Он встаёт в шесть утра. – He gets up at six a.m.

You wouldn’t normally say ставить будильник в шесть утра to mean “set it so that it rings at six”; that sounds more like “he sets the alarm at six a.m.” (time when he is doing the setting), which is not what we want.

So: на шесть утра = target “for six”; в шесть утра = time when something actually happens.

What exactly does к восьми mean? Is it “at eight” or “by eight”?

К восьми with the preposition к and dative case means roughly “by eight o’clock”, often with a nuance of “by around eight / towards eight”, i.e. not later than about eight.

So в школу ему к восьми ≈ he has to be at school by eight (o’clock).

Compare:

к восьми – by (towards) eight
в восемь – (exactly) at eight

Examples:

Приходи к восьми. – Come by eight (you should be there around eight, not later).
Поезд отправляется в восемь. – The train leaves at eight (exact fixed time).

In the sentence, к восьми matches the idea that school starts around eight / he should arrive by eight, not that some event happens exactly at eight on the dot.

Why is восемь in the form восьми here? What case is that?

Восьми is the dative singular form of восемь (“eight”).

The preposition к (“to, towards, by”) normally takes the dative case, so:

к пяти – by five
к шести – by six
к восьми – by eight

So grammatically:

к (preposition) + восьми (dative) = к восьми – “by eight”.

In в школу ему к восьми, why is there no verb? How can that be a full clause in Russian?

This is a very common elliptical (shortened) structure in colloquial Russian.

The full version would be something like:

хотя в школу ему нужно к восьми
хотя ему в школу к восьми (with нужно / надо implied)

Here, a verb such as нужно / надо / приходится (“need, must, have to”) is omitted but understood from context. Russian often drops such “obvious” words in informal speech or writing.

So:

…хотя в школу ему к восьми.
≈ “although he needs to be at school by eight.”

Even without an explicit verb, Russian speakers read ему (dative) + place/time as “he is supposed/required to be there then”. This is natural and idiomatic, especially in conversation.

Why is ему in the dative case here? What does that add, compared to он?

Ему is the dative form of он (“he”). In this pattern, the dative expresses obligation, necessity, or something that is relevant/required for the person.

The idea is:

ему в школу к восьми
≈ “it is (necessary) for him to be at school by eight” / “he has to be at school by eight.”

This is a very productive pattern in Russian:

Мне завтра рано вставать. – I have to get up early tomorrow.
Нам пора домой. – We should go home.
Тебе на работу к девяти. – You have to be at work by nine.

So ему in the dative doesn’t just say “he”; it encodes something like “for him, there is the requirement/need that…”. That’s why the dative fits with the implied нужно/надо in this sentence.

Why is it в школу and not в школе? What case is школу, and what does that change?

Школу here is accusative singular of школа.

With the preposition в, the case tells you the meaning:

в школу (accusative) → motion, direction: “to school”
в школе (prepositional) → location: “in/at school”

In в школу ему к восьми, the idea is “he has to go to school by eight” (direction, arrival), not “he is in school at eight”.

So:

Он идёт в школу. – He is going to school.
Он в школе. – He is at school.

Hence the accusative школу after в.

What is the role of хотя here? Does it require any special tense or mood, like a subjunctive?

Хотя is a concessive conjunction, meaning roughly “although / even though”. It introduces a fact that contrasts with or makes surprising what was said before.

Russian does not have a separate subjunctive form like many European languages. Хотя simply connects two clauses; the verbs stay in their normal tense/aspect:

Зачем‑то он ставит будильник на шесть утра, хотя в школу ему к восьми.
– For some reason he sets the alarm for six a.m., even though he needs to be at school only by eight.

Other examples:

Хотя было поздно, он продолжал работать. – Although it was late, he kept working.
Хотя дождь шёл весь день, мы пошли гулять. – Even though it rained all day, we went for a walk.

So хотя just signals “contrast / concession”; the grammar of the verbs stays otherwise normal.

Is the word order fixed? Could I say Он зачем‑то ставит будильник… or Хотя ему в школу к восьми instead?

The word order here is fairly flexible, and both of your variants are natural:

Moving зачем‑то:
- Зачем‑то он ставит будильник… (original)
- Он зачем‑то ставит будильник…
Both are fine.
- With зачем‑то at the beginning, you slightly emphasize the “for-some-strange-reason” part first.
- With он first, you start with the subject more neutrally.
Second clause variants:
In speech you will hear:
- …хотя в школу ему к восьми.
- …хотя ему в школу к восьми.
Both are acceptable. Ему can go before or after в школу without changing the basic meaning; the difference is only in slight emphasis and rhythm.

Russian word order is relatively free, but ordering affects which part is highlighted. The sentence as given is very typical colloquial order, but your alternatives are also correct.