This paper considers a curriculum design motivated by a desire to explore more valid pedagogical approaches that foster critical thinking skills among students engaged in an Environmental Science course in South Africa, focussing specifically on the topic of Citizen Science. Fifty-three under graduate students were involved in the course, which was run over a two week period. Data were generated from several sources, including individual student evaluations, a focus group discussion, lecturer reflections and summative assessment results. During the course, the development of critical thinking skills was scaffolded by different thinking approaches to the possibilities and problematics of student-selected case studies, followed by a collaborative re-examining of "what is known" about Citizen Science. Spiralling engagement with various resources harnessed the diversity of the class, as they drew on their personal and disciplinary backgrounds. The insights highlight possibilities for alternative higher education teaching models for emerging subjects such as Environmental Science, where the competencies required of graduates, such as critical thinking and coping with uncertainty, differ significantly from traditional "science" competencies, and therefore require a departure from traditional teaching methods.