Interactive Dichotomous Key for identifying rocks: a proposal to use with high school students

Abstract

The Estremoz Science Center has as main objective the dissemination and scientific literacy of population, with special emphasis on Earth Sciences. Recently, it has developed an unprecedented tool for identifying rocks: a dichotomous key called “What rock is this?” This key is the result of an extensive reflection and conceptualization that had as main goal the application of the concept of dichotomous key to Earth Sciences, which is remarkably rare, namely to the identification of common lithotypes. This dichotomous key is innovative, once the beginning is totally random and the user can choose its own path. This tool is extremely powerful because, depending on the sample to be identified, the user can select the most visible and distinctive features to begin, contrary to traditional dichotomous keys that imply a fixed and watertight path. In addition, this key is identical for any type of rock, not starting from a previous knowledge of its nature (i.e., sedimentary, igneous or metamorphic) to classify the sample. The use of this dichotomous key must be understood as a supporting tool for the identification and classification of rocks, which can be fundamental for the Earth Sciences teaching, whether in a formal or non-formal environment.