Modern society is facing a number of changes that have great influence on the context of education, including the teaching of mathematics. Such changes set new standards and programs in mathematics teaching and bring new expectations from students. Although practitioners are familiar with the curriculum and the need to make changes in mathematics teaching it is still not entirely clear to them how they should do it. In addition, Hattie (2015b) found that many of the changes sought to be introduced in education are not effective enough so that special attention should be paid to them. Therefore, it is necessary to determine which changes and how they should be introduced in the teaching of mathematics in order to contribute to better student's results. The aim of this research was to achieve essential changes in mathematics teaching by combining two types of research -a systematic literature review and an action research. The systematic review of the literature was aimed at determining the characteristics of effective mathematics teaching that contributes to better learning outcomes of primary school students based on the analysis of selected (quasi)experimental research. The analysis of relevant literature identified the following features of effective mathematics teaching: determining mathematical goals that lead to learning respecting student's prior knowledge, using tasks that promote reasoning and problem solving, conducting meaningful mathematical discussion, building procedural knowledge of conceptual understanding, using technology, collaborative learning, feedback information. Qualitative analysis of the programs included in the systematic review shown that effective interventions use tasks that promote inference and problem solving, provide quality feedback, respect student's prior knowledge, and use technology. In addition, it was found that it is not enough to apply only one feature, but it is necessary to include and combine different features of mathematics teaching that have proven to be effective based on research results. Thus, in the teaching of mathematics it is important to change the methods of teaching and learning. In that way, teaching adapts to the different possibilities and interests of students and enables their greater engagement. The action research aimed to improve the quality of mathematics, teaching in the second and third grade of primary school using the results of systematic review of relevant and recent research. The introduction of changes had a special impact on student's problem solving, which promote reasoning, the use of concrete material, which had a positive effect on student's activity and satisfaction with teaching mathematics. Teaching changes are necessary to lead to better students performance in mathematics. Whether this will be done depends primarily on the high motivation, personal, commitment and perseverance of a teacher. Based on this research, it is possible to conclude how important it is for a teacher to be ready to work on his professional development which should contribute to information about the features of effective teaching and the introduction of changes with systematic monitoring of the result of this process. The basic scientific contribution and originality of this research is reflected on connecting the results of systematic review of the literature and achieving changes in mathematics teaching through the action research, which has so far been used neither in Croatia nor in the world.