Because of its exceptional beauty and biodiversity, each national park represents interesting and informative content that keeps students attention, motivates them and encourages the work. An important task of education is literacy of individuals on the acquisition of knowledge of natural and social processes and knowledge about the importance of environmental protection. Organization of outdoor forms of teaching emphasizes the importance of gaining direct experience of the environment, nature, society and the natural and cultural heritage. Contemporary student should be able to integrate in diverse activities, encouraged to preserve natural resources and to promote life of harmony with nature. The thesis is supposed to derminate fourth grade student's knowledge about Croatian nacional parks. It emphasizes importance of knowledge about environmental protection and preservation of areals which abound with endangered floral and animal species. It emphasizes out the importance of outdoor education which is vital for acquiring direct experience about environment, nature, society and about natural and cutural heritage. Despite of unorganized outdoor activities in surveyed schools, the students displayed sufficient knowledge about Croatian national parks. The thesis compares the knowledge of those students who have visited one of the Croatian national parks in contrast of those who haven's. The results suggest that students who have visited one of the Croatian national parks had more correct answers and were more successful in the survey than those who haven't. The research also includes potentional differences between sexes in knowledge about Croatian national parks and concludes that male students were more familiar with facts presented in the survey than their female colleagues.