This study aims to determine what pre-service teachers know about the path of water through the body, and how they intend to explain this knowledge to five-year-old preschool children. This study aims to see the opportunities young children in preschool can obtain from an explanation of the nature of science related to an everyday life activity. A questionnaire was distributed to 42 pre-service teachers participating in the study. They study part time at the university (75% studying and 25% working), and most of the students are or have been working in preschools. All the students have passed the mandatory science courses. Data were collected through a questionnaire where the students explained their knowledge using drawings, and explaining pedagogic standpoints in open-ended questions. The results concluded that four pre-service teachers could sufficiently explain the workings of three organ systems. However, only one of the four intended to mention the three systems necessary for providing a coherent explanation of the body to a five-year-old child. Even the pre-service teachers who could describe more than one system did not intend to explain what they knew to the children. A typical response from the students was that they would seek facts together with the child.