This lesson plan is designed to help students review their knowledge of the human immune system through an interactive game called, Defend Your Body. Students will explore instances in which the body's immune system may malfunction. The first par of the lesson will review the main functions of the human immune system through a game called Defend Your Body. After playing the game, students will engage in a class discussion about the similarities of the gameplay and the function of a real immune system. During the second part of the lesson, students will revisit the game, to recognize instances where the human immune system may deviate from its normal functions. Students will then research various diseases that affect the immune system and create a new variation of Defend Your Body that simulates the effects of the disease.