Questions & Answers about Studenterna har ett möte med sin lärare imorgon.
Because sin is the reflexive possessive that refers back to the subject of the clause. Here it means “the students’ own teacher.” Using deras would normally mean “someone else’s teacher.”
- Correct: Studenterna har ett möte med sin lärare imorgon. (with their own teacher)
- Different meaning: Studenterna har ett möte med deras lärare imorgon. (with another group’s teacher)
- Similarly, hans/hennes would refer to some specific man’s/woman’s teacher, not the students’.
In Swedish, sin/sitt/sina agree with the possessed noun, not with the subject. The possessed noun here is singular (lärare, “teacher”), so you use singular sin.
- If it were plural: Studenterna har ett möte med sina lärare (“with their teachers”).
- If you want to stress one teacher each (distributed): Studenterna har möte med var sin lärare.
- sin = with an “en” noun in singular (e.g., sin lärare)
- sitt = with an “ett” noun in singular (e.g., sitt möte)
- sina = with any plural noun (e.g., sina lärare, sina möten)