I found this while searching for lesson plan help…figured that classroom teachers could use another resource, and this one is a good one, depending on the age group you teach. PBS has put together a comprehensive plan for introducing students to the roots of Modern Dance in America.
There is a radio story to listen to as well as plenty of ideas for discussion, and you will even find activity sheets that you can print out. Use everything they have provided–or customize your own lesson plan based on some of the ideas from here.