一期一会, ichi-go ichi-e, literally means "one time, one meeting". This Japanese idiom describes the ephemeral nature of every moment in life. In my opinion, the idea, originally from Japanese tea ceremony, permeates Japanese culture.

In the context of teaching, I interpret this idiom as "every moment is unique even if you are with the same people (students) in the same place (classroom)". I teach Japanese with this concept in mind and let my students interpret this concept in their own way through my teaching and cultural events.