Can your students tell the difference between a relationship where both species win, one wins and the other is unaffected, and one wins while the other suffers? This 25-question scenario-based set challenges students to classify symbiotic relationships as mutualism, commensalism, or parasitism through detailed ecological scenarios drawn from terrestrial, marine, and freshwater ecosystems. No definitions to recall — just applied ecological thinking about who benefits, who is harmed, and who is un