This study investigates what prior knowledge the students in the teacher programs have about the path of water through the body when they start taking the science courses and what their intentions are, i.e. what they think or believe is important knowledge, as they will later teach. The empirical data for this study is collected in a group of teacher students specializing in grade f-3 and grade 4-6. The information is collected via a questionnaire that consists of a drawn figure where the students draw and describe what they think is happening in the body from when they drink water until the liquid is urinated out. Besides, there are several knowledge questions on the same survey with multiple-choice alternatives and some open-ended questions relating to their future profession as teachers. The results show that the teacher students' prior knowledge is like that seen in previous studies when they connect more than two organ systems is problematic. Nearly a third had nonscientific explanations. These students stated that the most important they want to teach their pupils is the function of water but there were only 12 of 48 who answered that the transportation of nutrients and heat regulation.