Well, no, at the minimum he talked to all 25 students.[^1]

Additionally, why would 1, 3, or 25 matter?

The behavior Chris described requires attending the school and visiting it often enough to view multiple cohorts.

[^1] When I went into the classroom at the appointed hour, the 25 students were all there ready to interview me.

[^2] Man, I wish I went there if it means you could talk like this all the time. The older I get, the more suffocated I am by the damp blanket of adult communication. At 20 I would have said it was immoral and boring to withhold engaging deeply, at 35 I need a damn good reason to bother engaging rather than smiling and nodding.