From my experience of teaching the text to college freshmen and sophomores, the teaching of it in high schools would only serve to confuse students. The teacher's role, rather, should be to make students arrive at that conclusion through some strategies. Being an abstract play, one that violates almost all the conventions of playwriting and perhaps the first of the kind students would be reading, it would be helpful to first assign the reading of the first act and to ask students to come to the next class meeting prepared to discuss their emotional responses to the text.
Every literary critic belongs to one or more interpretive communities.
The discussion, however, must not be done in an unorganized way. Finally, the discussion of the text can end with the teacher telling the students about the little that is known about Beckett's life and the philosophy that informs the text.