In this article, the authors present the experience of developing environmental knowledge of junior schoolchil-dren using the example of the educational-methodological set “Baikal Chest”. The formation of environmental knowledge is relevant because we live on the coast of one of the unique natural sites of our country – Lake Baikal, which is the deepest and oldest body of water on planet Earth. Pedagogical conditions that increase the efficiency of this process are identified and justified. According to the authors, the most significant and effective pedagogical condition ns for the formation of environmental knowledge in primary schoolchildren are the use of interactive technologies, such as creative tasks, project activities, ICT-technologies, and problem situations. The article presents examples of tasks from the “Baikal Chest” educational complex, which, from the authors’ point of view, most effectively demonstrate the implementation of the ethno-regional component in the educa-tional process of elementary school, as well as form ecological knowledge of younger schoolchildren.