The purpose of the current study is to determine pre-school children’s opinions about the concepts of floating and sinking and the effect of the in class interactions on these opinions. To this end, a basic and interpretative qualitative study including one-to-one interviews with children was planned. A total of 20 children (66-73 months) attending a state pre-school were included in the study. Pre-study interviews were carried out with 5 of these children and post-study interviews were conducted with 6 of them. Parents of one of the 6 children participating in the post-study interviews were also carried out. The data were collected by means of semistructured interviews and video recordings during the experiments. Audio and video recordings were transcribed and then subjected to content analysis. The data collected in the pre-study interviews revealed that while the children used the terms such as “heavy-light”, “soft-hard”, “big-small”, “thin-thick” to explain the concepts of floating and sinking, the post-study interviews showed that they also used similar terms after the completion of the study. However, during the in-class discussions, two of the children were observed to try to explain the phenomenon of floating of objects through the buoyancy and these two children also continued to explain their observations on the basis of buoyancy concept in their post-study interviews. Though this concept of buoyancy was not mentioned in the pre-study interviews, it emerged during the classroom discussions, which helped the children who were familiar with it to remember. In the former studies conducted on children in this age group, the use of buoyancy concept was not encountered.