The article is devoted to the consideration of the educational and methodological support of the circle activities of children of preparatory groups of preschool educational institutions and primary schools of the cluster of continuous Cossack education in the framework of additional education. The additional education expands the possibilities for a child's personal development, awakens creativity and the ability to work on a specific topic in collaboration with a team of peers, with parents and with teachers. The authors emphasize the prospects of additional education at an early age, in kindergarten and in elementary school, which is important for the formation of a child's worldview. Additional education forms a variety of programs, orients children to different types of activities and different directions of search (practical, project, research), as well as various forms of associations, among which we have chosen one of the forms of additional education – a circle of interests related to the study of the history and culture of the Cossacks. The circle activity unites children, contributes to the solution of intellectual and educational as well as subject-practical tasks aimed at the formation of new knowledge and skills on a specific topic - the history and culture of the Cossacks, studied in educational organizations with an ethno-cultural Cossack component. For the successful implementation of educational and pedagogical processes in schools and pre-school children's educational institutions with an ethno-cultural Cossack component, at the request of parents and children, we have developed a Textbook for the alphabet for Little Cossacks and a Teaching manual for teachers on working with the Textbook. In the article we substantiate the possibility of effective use of the proposed methodology for conducting group work with children of preparatory groups of preschool educational institutions and primary school classes with an ethno-cultural Cossack component to form children's interest in the history and culture of the Cossacks, which will contribute to fostering a sense of patriotism, citizenship, respect for the heroes of our motherland as well as for the country's historical and cultural heritage. The authors of the study offer various forms of training within the framework of the circle activities: practical classes in the form of conversations, virtual and real excursions, contests, games.