This article reports an investigation of the intuitive scientific ideas and understandings of 321 preservice elementary teacher education students enrolled in the 2nd year of a 3-year program. The sample completed a physical science concept challenge instrument by responding, in writing, to open-ended questions about the concepts of floating/sinking, the nature of matter, air pressure and its effects, and the balance beam. Subjects' responses and explanations were analyzed, and response categories established. The results reveal that the majority of subjects, with the exception of a high proportion of those who had a successful senior high school background in physics and chemistry, have misunderstandings in these basic concept areas. It is argued that teachers should have a sound conceptual knowledge base in order to implement effective problem-solving strategies in the elementary science classroom. The importance of teaching science in elementary schools is widely acknowledged, therefore, teacher educators must identify and implement more effective strategies for science instruction in preservice teacher education courses that will enable all students to construct scientifically accurate concept knowledge.