I find it most interesting and engaging to use a variety of sources to distribute information to students prior to a musical activity. It is important to again note that this unit is intended for a general music class, where most of the time should be spent responding to, creating, and/or performing music. The historical information, which is incredibly valuable to the musical process that will follow, should be presented during roughly the first third of the class period, and possibly include some take-home elements. The remaining two-thirds of the period should be used for music-making.
I also like to provide students the opportunity to work alone, in a small group, and as a whole class ensemble. Depending on the class and the lesson, you may even offer students the choice of working with a small group or partner, or working alone. I have provided one lesson each to address the broad areas of creating, performing, and responding/connecting, as outlined in the National Core Arts Standards. Additionally, of the three lessons, one is written for the whole class as an ensemble, one for small-group work, and one as a chance to work independently.