Concepts of evaporation and liquefaction are of significance in both daily life and the school curriculum, yet misconceptions about these two phenomena are frequent. To assess the extent of such misconceptions among third graders, a cluster sample of 132 of them from four schools in four provinces was selected and then given a test consisting of ten open-ended questions. Additionally semi-structured interviews were also conducted. The data analysis revealed many misconceptions about these two phenomena and the effects of heat on them. Third graders participating in the study, in many instances, were unable to utilize their knowledge of evaporation and liquefaction properly. It is necessary that more attention be paid to these concepts in re-designing the curriculum.