This cooperative lesson plan has students analyze documents from a helicopter crash in Laos during the Vietnam War. At the time of the crash the mission was to evacuate troops that were being attacked by the Vietcong. Two of the bodies were never recovered. Students will analyze documents from the investigation and decide if the two missing Marines were killed in the crash or if they were missing in action. Enclosed in this lesson plan is 14 page paper I wrote that was published on a Vietnam website providing you with all of the necessary background information you may need to supplement your instruction. Included in this lesson are documents and a cooperative learning rubric. This lesson plan was written using the PAR (Preparation, Activities, Reflection) format.