Acquiring observational competences is an important task in early science education. It helps children to make a transition from seeing to observing and developing scientific process skills and science concepts. Outdoor education is seen by many researchers as optimal way for learning about life sciences, therefore ongoing loss of human interactions with nature is viewed as one of the most fundamental challenges. Using quasi-experimental design, we evaluated the effectiveness of one educational program where participating preschool children learned about forest organisms through direct experiences in the forest (direct experiences) and the other program where children learned only in the classroom watching videos, books, played various table games, etc. (vicarious experiences). A total of 129 Slovene children aged 3-6 years were interviewed a week before, immediately after and six weeks after the end of the programs. Four tasks measuring their skills of observation were used in the interviews. The results indicate that both educational programs improved their scientific skills. Direct experiences lead to higher increase and persistence of acquired skills. Direct experiences are seen as crucial for development of specific scientific skills of observing and classifying forest organisms, but to certain extent some skills can be alternatively acquired through vicarious experiences.