The Wave on a String simulation is the basis for this activity.

This is a full unit of instruction for high school physics students on the topic of Waves.  It includes lesson plans, content support, chapter tests, homework problems, lecture presentations, and clicker questions.

This is the full collection of teacher-created lesson plans and labs designed to be used with specific PhET simulations.  Each resource has been approved by the PhET project, and may be freely downloaded.