In this activity, learners can play two card games related to endangered species, specifically North American amphibians. In version one, "Guess My Amphibian," a learner secretly selects a card and players take turns asking yes-or-no questions to identify the mystery amphibian. In version two, "Guess My Rule," a learner selects a secret rule about amphibians and players try to identify the rule. For an extra challenge, use string circles to form a Venn Diagram that players can use to sort the amphibians and play a more challenging version of "Guess My Rule." [Activity is publicly available through a web crawler capture on Archive.org.]