How can I analyze the themes in Among School Children?

Hi everyone,
I’m working on a paper for my college Poetry class and I’ve been studying William Butler Yeats’ poem Among School Children. I’m having a tough time pinpointing the major themes in the poem, especially how Yeats contrasts youth and aging. The poem also seems to focus a lot on the relationship between mothers, nuns, and children, but I’m not sure how to interpret that. Can anyone help me break down the themes, or point out specific lines or stanzas that really highlight the contrast between youth and age? Any analysis or advice would be greatly appreciated!