This study explores the extent to which an activity used in an elementary science methods course affected the preservice teachers' content knowledge, attitudes, and self-efficacy. The participants were 172 students enrolled in five sections of elementary science methods. Students participated in a 9-week investigation on life cycles using mealworms ("Tenebrio obscurus"). Multiple data sources indicate that most of the students had limited prior content knowledge about mealworms, expressed neutral attitudes toward mealworms upon first exposure to them, and were uncomfortable with the idea of having to teach with and about them. At the end of 9 weeks, content knowledge on mealworms had greatly improved. The preservice teachers' attitudes about mealworms and their self-efficacy about using mealworms with children had also improved.