This article presents an empirical study on an initial learning progression of energy, a concept of central importance to the understanding of science. Learning progressions have been suggested as one vehicle to support the systematic and successful teaching of core science concepts. Ideally, a learning progression will provide teachers with a framework to assess students' level of understanding of a core concept and to guide students towards a more sophisticated level of understanding. Taking existing research as a point of departure, developing a learning progression involves recurring cycles of empirical validation and theoretical refinement. In this article, we report about our efforts in working towards a learning progression of energy. First, we derived an initial learning progression by utilizing existing curriculum, research on students' understanding, and development of students' understanding of energy. Second, we used these sources of guidance to develop a robust measurement instrument, the Energy Concept Assessment (ECA), based on multiple choice questions. Third, we utilized this instrument to assess the understanding of N ¼ 1,856 students from three different grade levels, Grades 6, 8, and 10. Findings provided evidence that students from Grade 6 mostly obtain an understanding of energy forms and energy sources. Students of Grade 8 additionally demonstrate an understanding of energy transfer and transformation, whereas only students of Grade 10, and then only some of these students, achieve a deeper understanding of energy conservation. We discuss the implications of our findings against the background of existing research on students understanding of energy. Finally, further steps in working towards a learning progression of energy are identified. ß

This paper examines students' achievement and interest and the extent to which they are predicted by teacher knowledge and motivation. Student achievement and interest are both considered desirable outcomes of school instruction. Teacher pedagogical content knowledge has been identified a major predictor of student achievement in previous research, whereas teacher motivation is considered a decisive factor influencing students' interest. So far, however, most research either focused on knowledge or motivation (both on the students' as well as the teachers' side), rarely investigating them together or examining the instructional mechanisms through which the supposed effects of teacher knowledge and motivation are facilitated. In the present study, N ¼ 77 physics teachers and their classes in Germany and Switzerland are investigated utilizing a multi-method approach in combining data obtained from testinstruments (teacher pedagogical content knowledge, student achievement) and questionnaires (teacher motivation, student interest, student perceived enthusiastic teaching) as well as videotaped instruction (cognitive activation rated by observers). Multi-level structural equation modeling was used to support the assumptions that teacher pedagogical content knowledge positively predicted students' achievement; the effect was mediated by cognitive activation. Teachers' motivation predicted students' interest which was mediated by enthusiastic teaching as perceived by students. Neither did teacher pedagogical content knowledge predict students' interest, nor teacher motivation students' achievement. This implies that in order to improve students' cognitive as well as affective outcomes, both teachers' knowledge but also their motivation need to be considered. motivation need to be considered.

Teachers' professional knowledge is assumed to be a key variable for effective teaching. As teacher education has the goal to enhance professional knowledge of current and future teachers, this knowledge should be described and assessed. Nevertheless, only a limited number of studies quantitatively measures physics teachers' professional knowledge. The study reported in this paper was part of a bigger project with the broader goal of understanding teacher professional knowledge. We designed a test instrument to assess the professional knowledge of physics teachers (N = 186) in the dimensions of content knowledge (CK), pedagogical content knowledge (PCK), and pedagogical knowledge (PK). A model describing the relationships between these three dimensions of professional knowledge was created to inform the design of the tests used to measure CK, PCK, and PK. In this paper, we describe the model with particular emphasis on the PCK part, and the subsequent PCK test development and its implementation in detail. We report different approaches to evaluate the PCK test, including the description of content validity, the examination of the internal structure of professional knowledge, and the analysis of construct validity by testing teachers across different school subjects, teachers from different school types, pre-service teachers, and physicists. Our findings demonstrate that our PCK test results could distinguish physics teachers from the other groups tested. The PCK test results could not be explained by teachers' CK or PK, cognitive abilities, computational skills, or science knowledge. ARTICLE HISTORY

The German education system does not traditionally rely on standardized testing. However, when the Programme for International Student Assessment (PISA) study revealed an average performance of German students compared to other participating countries, a particular proportion of low-performing students, and remarkable disparities between the federal states, German policy makers decided for a major reform of the education system. A core piece of this reform was the introduction of National Education Standards. For science education, these standards were heavily influenced by the PISA results and its underlying framework. That is, with the standards, a paradigm shift took place from the German notion of Bildung towards the AngloAmerican notion of literacy. With the introduction of these standards, a new field of empirical educational research was created: research on models of scientific literacy or competency models as a basis of benchmarking the standards. This article describes the German education system before PISA, summarizes the major findings from PISA, and describes how these findings informed the formulation of the performance standards for science education. It also details the measures undertaken to benchmark these standards. Finally, it provides insight into the issues with developing and benchmarking performance standards and points out future areas of research on evidence-based decision making in educational policy.

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