Learning about linear relationship with one unknown, middle school students may often demonstrate a certain degree of proficiency manipulating algebraic symbols. When encouraged, they can verbalize and explain the steps they perform, thereby demonstrating awareness of the procedures with symbols according to fixed rules. It is well known that correct and seemingly fluent procedural skills are not always supported by conceptual understanding. Previous research suggests that one of the indicators of conceptual understanding is the ability to recognize structurally the same relationship posed via multiple representations. The purpose of this study was to examine whether there is an association between middle school students' achievement level on standardized test, their ability to recognize structurally the same relationship presented in different modes and their ability to solve problems involving linear relationship with one unknown posed in different modalities. The study was conducted with a relatively large sample size (N = 443) of 7th and 8th grade students from one underperforming urban district. The student achievement level was measured by mathematics portion of the statewide Comprehensive Assessment System (sCAS). (Contains 6 tables and 5 figures.)