I think it's worth watching all 18 minutes, which includes three songs. If that's too much, you could easily select key sections.
Depending on the curriculum, you can tie some written reflection questions to songwriting, thoughts on his performances (I liked them, but they're not perfect) or the students' favorite songs or artists. All of this, of course, would tie in or culminate in Foreman's call to find and live their song.
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