Prior knowledge of students: essential aspects that a nursing expert professor identifies, interprets, and organizes to foster learning.

Objective: To analyze the essential aspects that the nursing expert professor identifies, interprets, and organizes during classroom dialogic processes with students to foster their learning.

Methods: Qualitative study, part of a multicenter study, which used ethnography of communication specifically from a micro-ethnographic approach. An expert professor from the Faculty of Nursing at a public university in Medellín, Colombia, was selected for the study. The fieldwork was done in three stages: 1:non-participant observations in two in-person classes of the Morphophysiology course recorded on video from two different perspectives (one focusing on the professor and another on the students); 2:think-aloud interviews with the professor and five students (three from the first class and two from the second) who spontaneously started more than two communicative interactions with the professor during the classes; and 3:parallel transcriptions, organized in didactic sequences (videos). The analysis was supported by the unit Student-Professor (identification-evaluation-answer) Student [S-P(i-e-a)S'], and by continuous comparisons of the data.

Results: Four categories were identified: 1: Identification of essential aspects: importance of prior knowledge, 2: Interpretation: connection between essential aspects and students' mental processes, 3: Organization of the answer: connection between prior knowledge and new knowledge, and: 4: Synchronization with the learning needs of the students, which were grouped in a meta-category: Prior knowledge of the students: essential aspects for learning.

Conclusion: Students' experiential prior knowledge constitutes the essential aspects identified, interpreted, and organized by the expert professor to achieve significant learning.