Global warming is one of the most serious environmental challenges we are facing today. Two science topics are important for students to understand how and why people's everyday energy consumption activities contribute to global warming. These two topics are: carbon-transforming processes and energy. They have been recognized as core content topics for many years in both science standards and curriculum However, empirical research has uncovered that current school science learning was not successful in helping students to use knowledge of these two topics to explain how people's everyday energy consumption activities contribute to global climate change over time.

This study uses the approach of learning progressions—sequences of successively more sophisticated ways of reasoning about science topics (National Research Council, 2007)—to study K-12 students' understanding of energy as it relates to socio-ecological events that contribute to the global climate change. I develop a learning progression framework that describes increasingly sophisticated ways of reasoning students display in their explanations of socio-ecological events, use the learning progression framework to measure students' achievement in written assessments, and use the learning progression framework to investigate mechanisms of students' progress.

Students from 4^th grade to 11^th grade in suburban and rural schools of a Midwestern state participated the research. I used both interviews and written assessments to elicit students' accounts about energy and the socio-ecological events. I found that the differences between scientific explanations and students' intuitive explanations are reflected in two aspects of learning performances—Association and Tracing. I also found that, instead of using energy, students with less science background tended to use informal entities such as "natural ability" and "vital power" to make accounts. Based on these two findings, I developed the learning progression framework: (1) Natural ability: to associate natural ability loosely with various aspects of the events and trace the macroscopic action-result chain; (2) Vital power: to associate vital power with enablers and trace the power-result chain; (3) Energy: to associate energy with energy indicators and trace energy unsuccessfully; (4) Energy: to associate energy with energy indicators and trace energy across scales successfully.

I used the learning progression framework to measure students' achievement and found that most students did not achieve Level 3, at which the reasoning based on energy conservation began to develop. I also used the learning progression framework to investigate mechanisms of students' progress. I found that students tended to rely on relatively cohesive and consistent reasoning to account for events. They often construct coherent synthetic reasoning by using strategies to reconcile features of scientific knowledge learned from school with their existing force-dynamic reasoning. The results of this study contribute to the emerging theoretical understanding and empirical basis of learning progression research.