An ongoing challenge for science teachers is to find teaching approaches that simultaneously challenge students, increase their retention and comprehension of content, and incorporate hands-on, constructivist approaches to learning. Interactive computer keys, which enable users to identify to the correct species an unknown specimen (e.g., plant, butterfly, bird specimen), have considerable potential at the secondary and tertiary levels as a constructivist teaching tool. At the secondary level, interactive keys can provide an opportunity for students, working alone or in groups, to try and identify the unknown specimen in hand. To operate an interactive key, students successively select traits ("characters") on screen that match the specimen, which progressively eliminates species that do match the selected characters. Eventually, a single species is indicated on screen as a match for the unknown. Images of the specimen then can be accessed to confirm the tentative identification. Usage of interaction keys should thus build students' observation skills and enhance their understanding of terms associated with descriptive organismal biology. At the tertiary level, students can build their own interactive keys based on collections they make themselves. At the University of Northern Colorado, students in Plant Taxonomy each build an interactive key to 20 specimens they collected and identified themselves. We use Lucid Professional 1.0 (www.lucidcentral.com), but other programs are available. Students have responded favorably to the use of interactive keys in this class. Student understanding of and familiarity with interactive keys is important, particularly at the tertiary level, given their increasing importance as diagnostic tools. Moreover, it is likely that within ten years, the use of interactive keys will be ubiquitous in organismal biology. Examples will be given of an interactive key and their construction, including suggestions on how they can be implemented successfully at the secondary and tertiary levels.

Key words: biology, constructivism, Interactive keys, secondary education, systematics