A dichotomous key is a great tool to use when teaching students how to classify organisms. This resource provides a way for students to practice using objects or organisms so that students become familiar with the "a" or "b" choices to form groups and eliminate choices in order to identify the correct organism by name. This key is for classifying shells of mollusks in the correct class by looking at shell characteristics. I would say this is an intermediate dichotomous key: Students have already learned how to do a dichotomous key. Students should already know the essential characteristics of mollusks and know the descriptions of the three main classes. Students should also know the levels of classification. This key can be used with real shell samples to help the student identify the mollusk and class.