In the following passage from the article "Using English in the Adult ESL classroom" by Kristen Lems, the author suggests that teaching through songs may expand students' cultural knowledge.
However, I do not quite understand the sentence in bold. Could you explain that to me please? It means perhaps that there might be some poems, videos, etc. connected with the theme of a song and that can supplement that song? That is, a teacher can make use of songs, poems, videos etc. that are somehow connected thematically in order to talk about foreign culture?

"Songs can be used in discussions of culture. They are a rich mine of information about human relations, ethics, customs, history, humor, and regional and cultural differences. A song can be part of a unit that also contains poems, video footage, or still photographs. Recordings of freedom songs from the civil rights movement can be a powerful accompaniment to watching Martin Luther King Jr.'s "I Have a Dream" speech on video, for example"