The quality of the interpersonal relationship between teacher and students. Rapport is widely considered a precondition for effective language learning because it lowers the Affective Filter, increases willingness to communicate, and enables risk-taking.
Dörnyei (2001) identifies rapport-building as foundational to his motivational framework. His three preconditions for motivation include: (a) appropriate teacher behaviours and a good relationship with students, (b) a pleasant and supportive classroom atmosphere, (c) a cohesive learner group with appropriate group norms. Without rapport, subsequent motivational strategies fail.
Rogers (1969) identified three core conditions for a facilitative relationship: empathy, congruence (genuineness), and unconditional positive regard, all directly applicable to rapport.
Rapport is not a soft skill peripheral to teaching; it is the infrastructure. Classroom management, Corrective Feedback, group work, and communicative activities all depend on students trusting the teacher and each other. A technically excellent lesson plan fails in a low-rapport classroom; a mediocre plan often succeeds in a high-rapport one.
Invest disproportionately in the first two weeks of a course. Early rapport-building pays compound returns for the remaining months.