Ability of understanding students` ideas and thinking is critical to teachers` professional growth. In this study, ``pedagogical reasoning`` was conceptualized as teachers` reasoning ability of students` misconceptions and possible causes of misconceptions when they hear and observe students` science discourses. To investigate elementary pre-service teachers` pedagogical reasoning levels, children`s science discourses on light reflection and electric circuit were video recorded and 43 pre-service elementary teachers were asked to identify children`s misconceptions and possible causes of misconceptions after watching the video clips. In conclusion, pedagogical reasoning levels of pre-service elementary teachers were not high enough, showing significant difference in light reflection and electric circuit. Possible explanations of this difference and educational implications were discussed.