This study aims to explore the middle schoolers' common naive conceptions of AI and the evolution of these conceptions during an AI summer camp. Data were collected from 14 middle school students (12 boys and 2 girls) from video observations and learning artifacts. The findings revealed 6 naive conceptions about AI concepts: (1) AI was the same as automation and robotics; (2) AI was a cure-all solution; (3) AI was created to be smart; (4) All data can be used by AI; and (5) AI had nothing to do with ethical considerations. The evolution of students' conceptions of AI was captured throughout the summer camp. This study will contribute to clarifying what naive conceptions of AI were common in young students and investigating design considerations for the AI curriculum in K-12 settings to address them effectively.