The cosine theorem is used in solving triangulation problems and in physics when solving problems of addition of unidirectional oscillations. However, this theorem is used only for the analytical calculation of triangles or when solving problems of adding two oscillations. Here we propose a generalization of the cosine theorem for the case of…

Development of three-dimensional (3D) printing technology has started a new chapter for in-classroom modeling of chemical molecules. The technology provides the opportunity to design and produce various types of personalized models. However, using classical 3D printers is time consuming, and it is hard to involve students in the modeling process…

The purpose of this note is to describe several challenging problems in Euclidean geometry. The note also contains author's solution sketches to the two problems.

Several articles deal with tilings with squares and dominoes on 2-dimensional boards, but only a few on boards in 3-dimensional space. We examine a tiling problem with coloured cubes and bricks on a (2 × 2 × "n")-board in three dimensions. After a short introduction and the definition of breakability we show a way to get the number of…

This article focuses on the experience of viewing polyhedra in modified kaleidoscopes, highlighting the perceptive acts that take place. It presents aspects of geometry, such as concepts and ideas involved in the visualization of polyhedra in kaleidoscopes, through an analyticalmathematical study of the reflection of images in mirrors and…

Learning curves are an important tool in cognitive diagnostics modeling to help assess how well students acquire new skills, and to refine and improve knowledge component models. Learning curves are typically obtained from a model estimated on real data obtained from a finite, and usually limited, sample of students. As a consequence, there is…

The paper discusses technology that can help students master four triangle centers -- circumcenter, incenter, orthocenter, and centroid. The technologies are a collection of web-based apps and dynamic geometry software. Through use of these technologies, multiple examples can be considered, which can lead students to generalizations about triangle…

The present study aims to examine mathematical creativity in students' work in geometry. Research conducted was based on two aspects: (a) examining the influence of geometrical figure apprehension on the production of multiple solutions and (b) how the necessity to construct auxiliary lines in the given shape promotes the production of multiple…

Windmill images and shapes have a long history in geometry and can be found in problems in different mathematical contexts. In this paper, we share and discuss various problems involving windmill shapes and solutions from geometry, algebra, to elementary number theory. These problems can be used, separately or together, for students to explore…

In this paper, Harel and Sowder's proof schemes of taxonomy were applied for identifying eighth grade students' learning of proof and proofing. This study aimed to examine what kind of proof schemes are used in geometry and measurement learning areas and student's skills in giving proof and their opinions about proof. Qualitative methods were…

This article presents a simple, fast, and equally accurate technique for measuring the area of a circle and of an ellipse without using geometric formulas. This therefore, together with the known radius of the circle and the semi-major and semi-minor axes of the ellipse, allows for the calculation of [pi]. The experiment is easy, thrilling, and…

This paper examines the relationship between early geometric skills, behavioral self-regulation skills, teacher-mother reported self-regulation skills, child age and family income in 5-6 year-old children. The participants (N = 202; 104 girls, 98 boys) average age was 71 months (sd = 4.82; Data on race/ethnicity were not asked to participants).…

Mastering mathematics in elementary school is essential for students because it provides the foundation to learn the subject at the secondary school and university levels. This study aimed to examine the effect of implementing the Outdoor Learning in Mathematics (OLM) method to increase elementary students' motivation and learning achievements in…

This article discusses the role of the three components of executive functions (EF) in geometric understanding. Discussing several examples of geometry problems, this article shows how EF are actively employed to solve geometry problems. Inhibition as the first component of EF helps the individual to suppress contextually irrelevant information.…

As a distinct mode of mathematical representation and communication, geometry diagrams are both signs that represent abstract geometric concepts and visual images that offer graphical-spatial properties. Dynamic geometly environment offers a wide range of tools for its users to create and interact with geometry diagrams. In this paper, I propose a…