The document describes a lesson plan for students to review the circulatory system through group work and role playing. It involves 4 stages: 1) Preparation where groups research characteristics of blood vessels, functions of blood, or effects of exercise; 2) Research where groups visit each other's "stalls" to learn; 3) Peer teaching where groups share what they learned; 4) A test on the circulatory system. The goal is for students to consolidate their knowledge through collaboration in a structured activity modeled after a market place.