The importance of extant biodiversity, concerns regarding the rising Anthropocene extinction rates, and commitments made by signatories to biodiversity conventions each increase demands for timely data. However, as species and conservation indicators become more complex, the less accessible they are to educators. New pedagogies are needed so that students can generate their own data for studies of biodiversity and extinction. I present a simple indicator of species diversity that examines declines in species' populations and whether or not these species subsequently recovered or faced extinction. Using such data, 14 threatened species are used as examples of the time taken for each species to reach a point of either recovery or extinction. The learning and pedagogical context for this information is reviewed, student use of the data demonstrated, and the lesson evaluated according to its learning objectives.