Tone, of the emotional weight of a poem, is difficult for many high schools students to apprehend, in part because they've had little practice, and in part because they have a limited affective vocabulary. One way to work successfully with tone is to ask students to create it for themselves by modeling--but in opposition--the work of a poet, in this case, Edgar Lee Masters.
Cain, Margaret T., "Manipulating Tone" (2012). Understanding Poetry. 12.