An effective instructional approach in elementary mathematics education has a significant role in the understanding of mathematical concepts and overall student achievement. We point out the characteristics, significance and effects that may be achieved in mathematics education through the application of project-based learning. The aim of the study was to examine the effects of project-based learning on student achievement in lower elementary mathematics education and examine whether the project-based model was equally acceptable to students with different marks. We arranged quasi-experimental research instruction (experiment with parallel groups), on a sample (N = 147) in order to examine whether an instructional approach based on the principles of project-based work would achieve better effects of learning and student achievement compared to the usual way of learning implemented in mathematics education. Results of the final measurements show that students in the experimental group, who worked according to the model of project-based work, achieved better compared to students who worked in the usual way. With this study we have shown that project-based instruction has significant effects on student achievement in lower elementary mathematics education, and that it can undoubtedly contribute to the methodological empowerment of teachers in their teaching practice.

This paper deals with precursory (propaedeutic) learning of the concept of number in the elementary mathematical education. The authors' objective is to suggest a method allowing for the increase of the effectiveness of interactive expansion of the concept of number by using a gradeappropriate learning framework for elementary mathematical education content. A theoretical background for the creation of this method is based on the description of various characteristics of precursory learning and interactive teaching of mathematics as well and the flexible differentiation approach. The paper especially emphasizes the possibilities of propaedeutic understanding of the concept of fraction and examine the effects of such approach in terms of student achievement in elementary mathematics education, on the basis of a methodological approach. Results obtained during the experimental research suggest that under the influence of the methodological approach of introducing fractions through propaedeutic learning, students achieve significantly better results in learning compared to students who have not used this method.

This paper points out the importance of developing critical thinking in the initial teaching of mathematics and highlights some of the problems associated with its realization. In this context, the authors draw attention to the definition of critical thinking and the role of content (tasks) in its development. Starting from the specificity of initial teaching of mathematics and students' age, critical thinking is operationalized through specific skills (formulation of the problem, reformulation of the problem, evaluation, sensitivity to the problems), that become apparent in work with mathematical content. On a sample of 246 students (9.5-10.4 years old), an experimental study (experiment with parallel groups) was organized in order to examine whether, with the selection of appropriate content (tasks), critical thinking in the initial teaching of mathematics can be developed. The results show that, with the appropriate choice of content, students' critical thinking, viewed as a whole, can be developed and that, in that process, we can significantly influence the development of each of its skills (formulation of the problem, reformulation of the problem, evaluation, sensitivity to the problems).

Correct understanding of the equals sign is the key to understanding arithme- tic, and a fundamental concept important for learning other areas of mathematics. Research around the world repeatedly mentions problems with correctly understanding the equals sign, emphasising the limited view of the equals sign as a command ”to calculate“ among students. The goal of the research was to identify the development of the concept of equality in line with the operationalised levels (operational, relational, and relational in the context of real-life prob- lem solving) and determine differences in understanding between students of the second (N = 190) and the fourth (N = 210) grade of primary school. The research was carried out using the testing technique. The research results show that students do not possess sufficiently developed relational understanding of the equals sign and that operational understanding prevails. Students of the fourth grade demonstrated better understanding of the equals sign at all levels of under- standing than the second graders.

The aim of this research was to examine the influence of differentiated tasks on the development of logical-combinatorial thinking abilities of the first grade of primary school students, using the experimental-research method. The research was conducted on the sample (N=60) chosen from the population of first-grade students of primary school "Nikola Tesla" in Novi Sad. Obtained research results showed the high influence of differentiated mathematical problems on students' logical-combinatorial thinking and functional knowledge in elementary mathematics education. The results' practical implication mirrors the possibility of their application in the domain of the improvement of students' cognitive abilities and functional knowledge from the very beginning of the educational journey.