The learning of scientific conceots is the conceptual change in the learner`s cognitive structure through the active interactions between the conceptual structure and related concepts to be learned. And the most important things students bring to science class are their previous concepts. In the light of a current paradigm. we may consider their conceots walid or invalid, naive or sophisticated, useful or disfunctional for additional learning. The objectives of this study is to answer the follwing question. 1. What kinds of misconceptions do students have about photosynthesis and evolution? 2. How do students develop their conceots about photosynthesis and evolution according to the grade levels? 3. Is there any difference in students` concepts about photosynthesis and evolution according to their living environment? 4. Is there any dirrerence in students` concepts about photosynthesis and evolution according to their sex? A total of 1,679 students from grade 4 to grade 10 were sampled for this study. The major findings of this study are as follows: 1. Students have many misconceptions about photosynthesis and evolution. And there is remarkable similarity between the misconeptions of students and the old concepts which previous scientists have had. 2. Students` concepts about photosynthesis and evolution develops as their grade levels proceed. 3. There is some difference between the development of students` concepts according to their living environment.