One major emphasis of reform initiatives in science education is the importance of extended inquiry experiences for students through authentic collaborations with scientists. As such, unique partnerships have started to emerge between science and education in an ongoing effort to capture the interest and imaginations of students as they make sense of the world around them. One such partnership is called the student-teacher-scientist partnership, in which teachers and their students participate in and contribute to the research of scientists. This article explores a partnership between a 10th-grade biology teacher, her students, and practicing scientists who collaborated in the design, implementation and evaluation of a horse evolution unit. The primary goal of the collaborative activity was to involve teachers and students in a process of conceptual change as a means of eliminating common misconceptions implicit in horse evolution displays in museums in various parts of the country. The evidence-based lessons developed enhanced students' understanding of concepts in macroevolution but also connected the science classroom with a community of scientists whose personalization of the horse evolution unit situated biological concepts and the learning experience within the context of real-world issues.