3D-printing technology has become increasingly important in recent years, offering many possibilities for mathematics teaching and learning. From our point of view, the field of calculus seems to be particularly suitable for the use of 3D-printing. Using the example of 3D-printed graphs of functions, the use of this technology in calculus is discussed within the three approaches of Grundvorstellungen, Subjective Domains of Experience and Empirical Theories. An empirical study, based on the qualitative content analysis according to Philipp Mayring, examines the influence of the models on concept formation processes in the context of derivatives. The focus is on the following research question: "What are the characteristics of concept formation processes of the concept of derivative in the context of 3D-printed graphs of functions?" Keywords 3D-printing. Derivative. Calculus. Grundvorstellung. Subjective domains of experience. Printed graphs of functions 3D-Printing in Mathematics Education 3D-printing technology is a relatively new tool with potential for mathematics education. It can be described as an additive manufacturing method allowing for digital models constructed with CAD-software to be transformed layer by layer into a real model made out of liquid plastic (see Gibson et al. 2014). Witzke and Hoffart (2018) detail three options for using the 3D-printing technology in the classroom. First, there is the possibility to reproduce Digital Experiences in Mathematics Education

Spatial ability is considered a major factor of intelligence and is increasingly important in times of digitization. This article explores the fostering of spatial ability through computer-aided design software. Different notions of spatial ability will be discussed, and, finally, a concept consisting of five aspects will be described. In addition, literature reviews on the connection between the use of computers and the fostering of spatial ability, as well as on the use of 3D printing technology in mathematics education, are given. Building on this, a case study is presented which examines the work of two middle-school students using computer-aided design software within a workshop at the University of Siegen. From the data material, basic possible actions within such software are derived. These are, based on theory, connected with the five aspects of the specific concept of spatial ability used. The results show various perspectives for the fostering of spatial ability with computer-aided design software.

Online learning platforms take over a new role in education, especially in times of the Covid-19 pandemic. This paper will discuss pre-service teachers’ reflections on attitudes towards online learning platforms and the respective changes due to an online training of using this digital tool in mathematics classes. The special training took place in a bachelor seminar with fourteen participants on the use of digital media in mathematics education at the University of Siegen. Based on the ‘Tripartite Model of Attitude Structure’ which defines the psychological concept of attitude, data material about the pre-service teachers’ attitudes is gathered by pre- and post-reflection-questionnaires. A qualitative content analysis led to the formation of a system of six main categories and approximately 51 descriptors for pre-service teachers’ attitudes towards online learning platforms and especially their changes due to the online training of using these platforms. The descriptors can be a basis for further research studies on this topic.

This article presents a possible framework for the cooperation of mathematics and physics education research domains. Moreover, the potential topics for such a scientific collaboration are explained by means of a structuring qualitative content analysis of current handbooks and conference proceedings in Germany and Vietnam. These topics can form a basis for further projects on the connection of subject-related didactics. One of these projects is an interdisciplinary course in teacher training at the Hanoi National University of Education (HNUE) as part of the Inter TeTra project between the HNUE and the University of Siegen.

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