Understanding the global carbon cycle will be a crucial part of environmental literacy in an era of climate change. However, students graduating from high school have trouble evaluating and contributing to scientific discussions about the global carbon cycle and human intervention in that cycle. As part of a five-year NSF funded Math and Science Partnership project focused on defining and improving environmental literacy, we are developing learning progressions to study student thinking and learning around the topic of global carbon. Learning progressions are empirically validated descriptions of increasingly sophisticated ways of thinking about or understanding a topic. We have administered written and interview assessments of middle and high school students in locations across the United States ranging from rural to urban. In prior work, our carbon learning progressions have focused on processes (photosynthesis, respiration, biosynthesis, combustion) and principles (conservation of energy and mass) necessary for understanding carbon and energy transformations at the scale of individual organisms or isolated events. Recently, we have extended the learning progression approach to study how student conceptions at organismal scales affect their ability to reason about larger scale processes.
Results/Conclusions
Our results show that students rarely employ scientific principles successfully when reasoning about the carbon cycle. When asked to explain familiar processes such as plant and animal growth, animal movement, or flames burning, we found that students frequently refer to the needs and “natural tendencies” of organisms or objects rather than principles of conservation of energy and mass. Accurate accounts of processes at both molecular and global scales are difficult for students with such a conception. For example, a pervasive refrain in student responses links plants and animals in a mutually fulfilling “carbon-oxygen” cycle in which animals breathe in oxygen and breathe out carbon dioxide while plants do the reverse. Our evidence shows that this conception can cause students to confuse the dangers of rising atmospheric carbon dioxide with running out of global oxygen. We are also exploring the importance of quantitative and graphical reasoning skills and students’ capacities for applying scientific reasoning in their personal investigations and decisions as citizens confronting the issue of human impacts on carbon and climate. Insights from our research will be used to inform innovative teaching strategies essential for improving environmental literacy in an era of climate change.
