Assessment is a procedure in education that can provide significant information, useful for improving education at different levels. Targeted planning of the teaching process, constructive selection and harmonization of teaching and learning methods with assessment methods and educational outcomes by the teacher opens up the potential for improving teacher teaching and student learning. Each component of assessment has the potential for quality implementation, which successively contributes to the ultimate purposes of assessment, such as motivation for learning, learning guidance, correction of learning errors, etc. The concept of this paper is based on the theoretical analysis of the notion of assessment and formative assessment at the level of the entire educational process and within the field of the subject of Science and Social Studies. This theoretical content is considered through eight chapters, from the conceptual definition of assessment, formative assessment in relation to other categories to ways of its application in the teaching of the subject Science and Social Studies. At the beginning of the paper, the notion of assessment is etymologically analyzed along with a review of literature in Croatian and English. Inconsistency in the terminology of assessment is observed, where the term for assessment (hrv. vrednovanje) in the Croatian language is used as a synonym for the terms evaluacija and valorizacija. In professional literature in English there is a certain overlap or complete distinction between the terms assessment and evaluation. The components as integrated parts of assessment and the principles of assessment as didactic foundations provide a framework for the development of the evaluation process in teaching. We correlate the axiological aspect of pedagogical science with the concept of assessment, because for assessment to be effective, productive and purposeful, it must have value in itself and the evaluator's internalized values are reflected in the assessment process itself. Educational policies determine the development of assessment, while each actor within educational policies (government bodies, the scientific community and teachers) bears responsibility for the implementation and execution of well-argued pedagogical and didactic evaluation methods. Assessment is a complex procedure whose form is determined by a number of different division criteria. This paper examines assessment theoretically in detail according to the criterion of the nature of evaluation, considering the relationship between summative and formativ assessment. It highlights their characteristics and the possibilities of their complementation and integration in teaching in order to more effectively achieve the purpose of assessment. Various research related to the field of formative assessment is listed in the theoretical part. The focus is on the approaches of formative assessment, assessment for learning and assessment as learning, and their connection with feedback, motivation, knowledge and satisfaction in school. The subject Science and Social Studies is presented in a contemporary context through a constructivist paradigm and a holistic approach. The contents of the Science and Social Studies course, which is characterized by completeness and comprehensiveness and the prevalence of phenomenologically oriented integration, enables the application of various formative evaluation techniques during all stages and types of lessons. This paper presents the techniques of formative assessment used in a quasi-experiment as the empirical research on which this paper is based. Their applications and connection with the development of cognitive, psychomotor and affective dimensions of the students’ personality are described. The empirical part of the research is based on a quasi-experiment, rarely used in educational research due to the necessary respect for high ethical principles as well as complex and demanding preparatory and logistical actions. The research was conducted in the 2020./2021. school year in seven primary schools in Zagreb, on a sample of 178 students. 14 fourth-grade classes participated, two classes from each elementary school. The research was conducted during the second educational period when formative assessment was introduced in the treatment groups, while in the classes that represented the control group, traditional evaluation continued with the control and equalization of all other available factors. The goal of the research was to determine the contribution of formative assessment in the teaching of the subject Science and Social Studies, in learning, motivation and satisfaction with teaching in relation to the traditional assessment model. The tasks of the research from which further hypotheses were derived were as follows: determining the connection between the application of formative assessment in the teaching of the subject Science and Social Studies and the level of knowledge of the content of the subject among students of the 4th grade of elementary school, determining the connection between the application of formative assessment in the teaching of Science and Social Studies and the motivation for learning the subject matter of 4th grade elementary school students and determining the connection between the application of formative assessment in the teaching of Science and Social Studies and satisfaction with teaching among 4th grade elementary school students. In conclusion, the described additional analyses confirmed the conclusions of the analysis of variance and support the hypothesized difference in the results of the Science and Social Studies knowledge tests - formative assessment led to better results of students from the treatment group in the first and second measurements after the intervention, although students from the control group and treatment groups achieved equal results before the intervention. As for motivation and satisfaction with the class, the results partially confirm the set hypothesis: although students from the treatment group achieved higher results on the measure of motivation and satisfaction with teaching than students from the control group after the introduction of formative assessment, it seems that these students were more motivated and satisfied even before the introduction of formative assessment teaching. Therefore, based on these results, the increase in motivation to learn the content of the subject of Science and Social Studies and satisfaction with teaching cannot be attributed to the introduction of formative assessment.