Learn Hardcore Spanish (Latin America): Cada alumno lee su propio libro en la biblioteca. - Each student reads their own book in the library.

In Spanish, when you use cada + singular noun (here alumno), you treat that noun as one unit at a time. Grammatically, cada alumno is singular, so it takes lee (él/ella). Even though you imagine many students, the structure focuses on one by one.

What does su propio libro mean, and why do we need propio?

Su propio libro literally means "his/her/their own book." Su libro could simply mean "his book" or even "the book assigned to him." Adding propio emphasizes ownership: it’s literally the book that belongs to that student, not a shared or borrowed one.

Could we say Cada alumno lee su libro without propio? Would the meaning change?

Yes, you could say Cada alumno lee su libro. It still means "Each student reads his/her book," but it’s less explicit about ownership. Without propio, listeners might wonder if it’s the book each one chose or a book they brought, whereas su propio libro clears up that it’s their personal copy.

Why is su used here? How do we know su refers to alumno and not someone else?

In Spanish, possessive adjectives (mi, tu, su, etc.) usually refer back to the subject of the clause unless context says otherwise. Here, the subject is cada alumno, so su links to alumno. If you needed to avoid confusion, you could say Cada alumno lee el libro que él/ella trajo or Cada uno lee su propio libro.

Why is libro singular instead of libros?

The sentence implies one book per student. Each alumno reads one book, so we use the singular libro. If you meant that each student reads multiple books, you’d say Cada alumno lee sus propios libros (using plural possessive sus and plural noun libros).

Why do we say la biblioteca with the definite article instead of una biblioteca?

When talking about places in general (schools, libraries, cafés), Spanish often uses the definite article: Voy a la escuela, están en la biblioteca. It treats the location as a familiar or generic place. Una biblioteca would introduce any library out of many, which sounds less natural when you mean "in the library" as the usual place.

Can we replace alumno with estudiante? Will it sound natural in Latin America?

Yes. Cada estudiante lee su propio libro en la biblioteca is perfectly natural. Alumno and estudiante overlap a lot. Some might say alumno more for primary or secondary school and estudiante for high school or university, but both are widely understood everywhere.

Could we change the word order to En la biblioteca cada alumno lee su propio libro? Any difference?

Absolutely. Spanish allows flexibility. Starting with En la biblioteca just shifts the emphasis to the location. The meaning stays the same, though starting with En la biblioteca might feel more formal or written.