This paper describes how a target group of seven students in a combined fourth and fifth grade mathematics class used structured representations to solve fraction problems situated within various realistic contexts. Emphasis is given to the ways in which students' thinking about rational number concepts influences and is influenced by the students' use of two structured representations. The first structured representation was a set of fraction strips the students used as a manipulative. The other structured representation was a ratio table, a pictorial model used flexibly by most of the students. Findings indicate that most of the target students did not connect their symbolic procedures to the underlying concepts, particularly when they tried to write formal addition sentences using the fraction strips. The findings also suggest that the ratio table afforded more opportunities for the students to apply their informal knowledge of fractions as quantities. Contains 28 references. (DDR)