This article presents an international study that documented the conceptions of atomic models held by 1062 in-service high school science teachers from 58 countries. First, a previous study on pre-service science teachers’ conceptions of atomic models was successfully replicated as a pilot study with an international sample of in-service science teachers. Teachers’ conceptions were investigated by analysing their drawings of atomic models. Based on these results, a multiple-choice questionnaire was developed for the main study. This questionnaire collected data on teachers’ conceptions of atomic models, teachers’ knowledge about their students’ conceptions of atomic models, and teachers’ use of atomic models in the classroom. The results show that the teachers’ conceptions of atomic models are almost evenly distributed over six different atomic models. These models are the Bohr model, the Rutherford model, the probability model, the orbital model, the probability orbit model, and the wave model. The vast majority of teachers assume that their students’ conceptions are centred on two historical atomic models, namely the Bohr model and the Rutherford model. Furthermore, the majority of teachers prefer to use historical atomic models over modern atomic models in the classroom. However, the findings also highlight that the use of modern atomic models in the classroom is positively correlated with growing teaching experience, and that teachers’ conceptions of atomic models and their knowledge of students’ conceptions of atomic models significantly influence teachers’ classroom practice.

Preservice mathematics teachers' beliefs about actions related to the use of the technological tools in teaching mathematics may affect how they are going to use them in their classroom activities. However, there is a limited evidence of what beliefs they hold on their intended actions of using technological tools in teaching mathematics. This study presents two preservice high school mathematics teachers' actional beliefs related to their intended actions in teaching geometric transformations (GTs) using Geometer's Sketchpad (GSP). The study comprised of a series of five task-based qualitative interviews with each of two senior undergraduate preservice teachers at a medium-sized public university in the Rocky Mountain Region of the United States. This study used a radical constructivist grounded theory (RCGT) with five assumptions—symbiosis, voice, cognition, adaptation, and praxis as a theoretical framework to guide the study process. The thematic findings of the study included four in vivo categories of their beliefs associated with actions of teaching GTs with GSP – assessment of student learning, engaging students in a group activity in exploring GTs with GSP, engaging students in individual activity in exploring GTs with GSP, and exploring GTs with GSP as 'suck it up and do it.' Pedagogical implications of these categories have been discussed.

This study compares experts' and teachers' conceptualization of pedagogical content knowledge (PCK). The study participants included teachers (n=20) enrolled in a graduate mathematics education course on PCK. Participants responded to two open-ended questions: a) describe in your own words what PCK is; b) provide an example of PCK. The responses were collected, qualitatively and quantitatively analyzed, and then compared to those suggested by experts to identify and describe the similarities and differences between teachers’ and experts’ conceptualizations using the Pareto analysis. Experts’ and teachers’ PCK components ranking was analyzed using the nonparametric Mann-Whitney U test. Even though the results of the quantitative analysis were not significant (e.g., the observed U-value is 32 whereas the critical value of U at p < .05 is 13), the qualitative discussion on the differences between expert and teachers’ ranking suggests insightful interpretation of priorities among PCK components across the two groups.