Create a list of all the resources you can find related to one particular concept you might teach. Be sure to search especially for materials that represent a diverse range of cultures, ethnicities and genders.

A concept that I plan on teaching is African American Spirituals. Here are some websites that apply to the subject:

http://www.sbgmusic.com/html/teacher/reference/styles/spirituals.html

http://arts.ucsc.edu/GDEAD/AGDL/rag.html

http://www.pbs.org/wgbh/aia/part4/4p2944.html

http://www.negrospirituals.com/news-song/swing_low_sweet_chariot_swing_lo.htm

http://www.negrospirituals.com/news-song/swing_low_sweet_chariot_swing_lo.htm