In this outdoor activity/game, learners use thermometers to simulate how lizards survive in habitats with extreme temperatures. Learners are challenged to keep their thermometer-lizard "alive" by keeping its temperature within a five-degree safe range. While regulating their pretend lizards' temperatures, learners must move the lizards through a course of sun and shade, trying to reach the finish first. Through the game and followup discussion, learners come to understand different ways that exotherms, or "cold-blooded" animals, regulate their body temperatures and how they differ from endotherms, or "warm-blooded" animals, such as humans. Activity must be done on a warm, sunny day in a site with areas of deep shade, bright sun, and broken or partial shade.