Search

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.

This study investigates students' conceptions of the carbon cycle with regard to the components they believe to be relevant to the carbon cycle, how they interrelate these components, the ways in which they trace carbon atoms, and the different levels of biological organisation they consider when doing so. A total of 142 students aged 13-16 years (grades 8-10) participated in the study. A total of 130 students completed the diagnostic task, and an additional 12 students completed both the diagnostic task and were interviewed. The primary results show that the students identified few components of the carbon cycle, tended to trace carbon atoms exclusively at the level of the organism, and had difficulties identifying organic carbon compounds, especially during processes in which carbon compounds are transformed. Considering the main educational implications, we recommend using an instructional strategy that traces carbon atoms across the different levels of biological organisation whilst connecting fragmented knowledge by integrating knowledge from physiology, biochemistry and ecology when teaching the carbon cycle.

The aim of this study is to investigate the relationship between high school students' understanding of carbon compounds, including their transformations, and their ability to trace matter in the carbon cycle. The rationale of this study is based on the hypothesis that the students' lack of knowledge about carbon compounds and their transformations limits the students' ability to trace carbon in the carbon cycle. A total of 16 students aged 14-16 years (grade 9) from two different secondary schools were interviewed about carbon compounds, and they were asked to trace matter in the carbon cycle in response to a written diagnostic task. We argue that students' lack of knowledge about carbon compounds and their transformations is responsible for their construction of the carbon cycle as either a gas-gas or solid-solid cycle. Educational implications are discussed.