Can prospective elementary teachers "unlearn" harmful algorithms used with fractions as they are invited to develop fraction number sense? This study examined the development of prospective elementary teachers' fraction number sense during an intermediate (grades 5-8) mathematics methods course. During this course, participants' were involved in a variety of activities and tasks used for the development of fraction number sense. Examination of participants' scores on the fraction sense pretest/posttest scores revealed that participants scored significantly higher (t(41) = -5.632, p less than 0.001) on the posttest. While these results are positive, further analysis revealed that this group of prospective elementary teachers brought with them a limited understanding of fractions to their mathematics methods courses and that despite a concentrated effort to improve those understandings, only minimal progress was accomplished. (Contains 5 tables and 1 figure.)