Восьмой студент сидит у окна.

to sit

Breakdown of Восьмой студент сидит у окна.

• у: by
• окно: the window
• студент: the student

Questions & Answers about Восьмой студент сидит у окна.

Why is восьмой in that form instead of восьмая or восьмое?

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.