This study compared the performance of students using the Science Writing Heuristic (SWH) approach and students using a standard or traditional laboratory curriculum on lecture exams and a laboratory practical exam on a specific topic, chemical equilibrium. The SWH helps students do inquiry science laboratory work by structuring the laboratory notebook in a format that guides students to answer directed questions instead of using a traditional laboratory report format. In the SWH approach, students must make a claim (inference) about what was learned through the laboratory experiment and provide evidence to support that claim. Then, through group discussion, reflection and writing, students continue to negotiate meaning from experiments they conducted. Two teaching assistants were each assigned one standard lab section and one SWH lab section. Subjects in this study were students enrolled in a second-semester general chemistry course for science and engineering majors. A baseline chemistry knowledge score was computed for the subjects in this study. The standard laboratory group had a higher average baseline chemistry score compared to the SWH group. The results of an analysis of covariance indicated that the SWH students exhibited a better overall understanding of chemical equilibrium compared to students using a standard approach in the general chemistry laboratory. (Contains 3 tables, 2 figures, and 1 note.)