Fractions are one of the most difficult areas of mathematics for all students and especially for students with learning disabilities (LD). An incomplete understanding of fractions during the elementary and middle school may be why some students view fractions as "really small" or "less than 1" compared to others who view them as multiplicative magnitudes. We analyzed how one student with LD worked on tasks involving both whole numbers and fractions using the framework of units coordination. Through our analyses of 14 teaching experiment sessions, we determined that he was operating on two levels of units with whole numbers, but only one level of units with fractions. We argue that this limited his ability to operate multiplicatively with fractions. However, his identified LD did not appear to impact his work with the fractions tasks he was given. Implications for future research and instruction are shared. [For the complete proceedings, see ED606556.]