Students often have misconceptions about terrestrial carbon flows and there is a lack of coherence in students' explanations regarding the different levels of biological organisation at which these processes occur. In this study, problem-based teaching materials on the topic of terrestrial carbon flows were developed and tested with 15 students 18-19 years old (grade 12) using a pre/post-test design. Students focused on specific carbon flows in an ecosystem at the macro level (e.g. CO[subscript 2] fixation and heterotrophic respiration) including specific related concepts at the micro level (e.g. photosynthesis and cellular respiration). The findings indicate that the teaching materials improved the students' understanding of terrestrial carbon flows and their ability to reason across the different levels of biological organisation. On the basis of these findings, implications for teaching terrestrial carbon flows in biological education are discussed.