Speciation provides a framework for classifying biodiversity on Earth and is a central concept in evolutionary biology. To help undergraduate students learn about speciation, we designed a student-centered lesson that uses active-learning techniques (e.g., clicker questions, small group work, and whole class discussion) and compares multiple species concepts (morphological, biological, and phylogenetic) using giraffes as an example. Giraffes were chosen as the focus of this lesson because they are familiar and have broad appeal to students; are in danger of becoming extinct; and have ecological, economic, and cultural importance. Students also learn about contemporary giraffe conservation issues and the current debate in the literature regarding the total number of giraffe species. Students then apply their knowledge by working in small groups on speciation scenarios that highlight organisms across the tree of life. Student understanding is assessed using multiple-choice pre/post-test questions, in-class clicker questions with peer discussion, and exam questions. Here we provide details about the lesson and report that student learning is improved.