This diploma thesis deals with the inclusion of project days in Natural history lessons at elementary schools in Most and nearby villages. The diploma thesis is divided into three parts. The theoretical part is devoted to origin and history of project-based learning in the world and in czech schools, theoretical concepts that are directly related to project-based learning, and also the incusion of project-based learning into present educational proces, advantages and disadvantages of project-based learning. The research part of the thesis and the main research problem focuses on using the project-based learning at primary school. The research part is the result of a questionnaire survey that I realized at selected elementary schools. In the process of researching was used a questionnaire method, which i sone of the most common tools for data collection. Teachers from these schools took care of completing the statistical data. The questionnaire was created and distributed electronically. In the practical part I present the project day "Tree Day" which I realized at lower secondery school Obránců míru in Most. KEY WORDS Project-based learning, project day, science teaching