In this study, we aimed to investigate the change in third-grade preservice elementary teachers' observation and inference skills. We also aimed to develop their ability to distinguish observation from inference. A total of 27 preservice elementary teachers participated in the study. Participants' preinstruction and postinstruction observation and inference skills were explored through written statements about three different drawings. An instruction on science process skills within Science Teaching course was provided to the preservice elementary teachers. Analysis of their pre and postinstruction observation and inference statements showed that, at the beginning, preservice elementary teachers were not adequate in observation and mostly confused observation with inference. After participating in classroom discussions and activities, they improved in making observation and inference. They showed better enhancement in making observation than drawing inference. Implications were suggested in terms of elementary teacher education programs and further research.