The emphasis of the educational reform currently underway in Bulgaria is on the formation of key competencies of the pupils. Mathematical competence is one of them. The mastering of basic mathematical knowledge in primary grades remains a priority. At the same time, specific mathematics curricula are explicitly laid out such as solving practical tasks, forming teamwork skills, search of information from different sources by the students themselves, project work, etc. In my research work over the past few years, I have tried experimentally with my own ideas for project work with primary school pupils. In this publication, I will present my concept of work on the project “Sofia – Capital of Bulgaria” for students of the fourth grade. It will integrate mathematical knowledge and skills with knowledge of Man and Society and a number of components of civic education. Mathematical knowledge and skills will include: adding and subtracting numbers over 1000 without passing, finding an unknown subtrahend, solving numerical expressions with parenthesis and without parenthesis, units of measure (meters, grams, kilometer, centimeter). From the knowledge and skills of Man and Society (Man and Society curriculum for the fourth grade at https://mon.bg/bg/2190), the topic: “Sofia – Contemporary Capital” is taken and the related competencies (tell about the location of the capital of Bulgaria with the help of a map; recognize on image the famous cultural monuments and natural assets of the Bulgarian capital; connect important sights of the capital with the historical ages to which they belong; understand the importance of the capital as a modern administrative centre of the country). Working on this project, pupils in the fourth grade will also acquire the following competencies: digital competence (using information in electronic form to produce short presentations on geographic, historical, cultural themes; using electronic presentations as a source of information about events and individuals); learning skills (working with maps and reference books – guides, children's encyclopaedias, extracting information about the past and the present from illustrative material, searching for information on a particular problem from written documents in the textbook); social and civic competencies (solving of problematic situations requiring hearing, exposing the personal point of view and maintaining one's own opinion; collecting curious facts about popular personalities or events from Bulgarian history; making albums with personal photos from visiting cultural, historical and natural sites; drawing up tables for the holidays of different communities – religious and ethnic; creating projects on a studied historical or geographic theme; visiting the municipality, the mayoralty, the National Assembly etc.; cultural competence and skills to express through creativity (making of albums with drawings from exhibits of visited museums, observation of natural and historical sites, elaboration of group presentations for selected natural sites). One of the distinctive aspects of the project activity with primary school pupils is the integrative nature of the project activities. The project “Sofia – Capital of Bulgaria” presented in this article is suitable for the first school term of the fourth grade. This is a medium term project that lasts for a month or two. It finishes with an open lesson in mathematics (one or two study hours), during which pupils resolve mathematical and application-practical tasks and present the results of their preliminary project work (preliminary project activities). Tasks in the project are three types: individual, group and class. Each pupil receives from all three categories of tasks. The task of the teacher is the preparation and distribution of the individual, group and class-related tasks, the determination of the deadlines for the implementation of the commitments undertaken by the pupils, as well as the ongoing control over the tasks.