Learn Hardcore Russian: Восьмой студент сидит у окна. - The eighth student is sitting by the window.

The noun студент is masculine, singular, and in the nominative case as the subject of the sentence. Ordinal numbers in Russian act like adjectives and must agree in gender, number, and case with the noun they modify. The masculine nominative singular form of “eighth” is восьмой, so it matches студент.

What case is студент in, and why is it in that case?

студент is in the nominative singular case because it is the subject of the sentence—the one performing the action (sitting).

What preposition is у, and why is it used here instead of в or на?

у means “by” or “at” (in the sense of proximity). It indicates that the student is sitting right next to the window.
• в would mean “in” or “into” (inside something)
• на would mean “on” or “onto” (on a surface)
Neither of those conveys “beside” the way у does.

What case is окна, and why does у require that case?

окна is in the genitive singular. The preposition у always governs the genitive case when expressing location “at/near” something.

There are no words for “the” or “a” in this sentence. How does Russian show definiteness or indefiniteness?

Russian does not use articles like “the” or “a.” Definiteness or indefiniteness is usually inferred from context, word order, or by adding demonstratives (этот, какой-нибудь, etc.). In this sentence, the ordinal восьмой (“the eighth”) already implies that it’s a specific student.

Can I change the word order, for example saying У окна сидит восьмой студент?

Yes. У окна сидит восьмой студент is grammatically correct.
• Starting with У окна puts emphasis on the location (“By the window”).
• The original Восьмой студент сидит у окна is more neutral and starts by identifying the student.

Could восьмой stand alone without студент, as in Восьмой сидит у окна?

Yes, if the context has already made it clear you’re talking about students. Then восьмой functions like a noun: “the eighth one.”
Example:
– Кто ещё отвечает сегодня?
– Восьмой сидит у окна.

Could I use возле окна instead of у окна, and would it change the meaning?

Yes, you can say сидит возле окна. Both mean “sits by the window,” but:
• у окна implies sitting immediately next to the window.
• возле окна suggests being in the vicinity of the window (possibly a bit farther away).

How would you ask “Which student is sitting by the window?” to get the answer Восьмой студент сидит у окна?

You’d ask:
«Который по счёту студент сидит у окна?»
Literally: “Which student by count is sitting by the window?” This invites an ordinal-number answer like восьмой студент.

How is восьмой pronounced, and where is the stress?

It’s pronounced [вос-мо́й] with the stress on the second syllable: восьМОЙ. The soft sign (ь) after “с” indicates that the “s” is softened ([с’]).