Present research aims to determine the effect of science activities on concept development of preschool period age 5-6 children groups. Parallel to research objective, qualitative research pattern has been the selected method. Study group comprises of collectively 48 children from 5-6 age group attending to a private education institution in city of Antalya. Prior to conducting the research literature scan has been performed to identify "the Earth, Sun and Moon" relevant concepts corresponding to the age level of participants. Parallel to the science-related concepts activities such as "Do you know our Solar System?", "Do the planets move?", "How are the movements of the Earth, Sun and Moon?", "What are the phases of Earth, Moon?", "How does night and day occur?", "How does the Earth look like from the Space?" have been implemented for a period of six weeks. In line with selected science-relevant concepts participants have been asked to draw pictures before and after the science activities while at the same time the researchers have recorded in writing what participants aimed to narrate via pictures. At the end of research it has been manifested that science activities is an effective technique in the acquisition of basic concepts related to "the Earth, Sun and Moon" as much as they positively affect development of already-existing concepts in children. (Contains 6 tables and 6 figures.)