This lesson plan is part of the DiscoverySchool.com lesson plan library for grades 6-8. Students research three types of symbiotic relationships between organisms in nature: mutualism, commensalisms, and parasitism. They report their research findings and hypothesize about how symbiotic relationships might have evolved. Included are objectives, materials, procedures, discussion questions, evaluation ideas, suggested readings, and vocabulary. There are videos available to order which complement this lesson, an audio-enhanced vocabulary list, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.