The importance of Computational Thinking (CT) as a goal of science education is increasingly acknowledged. This study investigates the effect of computationally-enriched science curriculum on students’ development of CT practices. Over the course of one school year, biology lessons featuring the exploration of NetLogo models were implemented in the classrooms of three 9th grade biology teachers at an urban public secondary school in the United States. One-hundred thirty-three biology students took both pre-and post-tests that were administered at the beginning and end of the school year. The students’ responses to relevant assessment items were coded and scored using rubrics designed to evaluate their mastery of two learning objectives relating to modeling and simulation practices. The first learning objective was to explore the relationship between a system’s parameters and its behavior. The second learning objective was to identify the simplifications made by a model. Each item’s pre-and post-test scores were compared using a Wilcoxon signed-rank test. Results indicate a statistically significant improvement with respect to the second of the two learning objectives, suggesting that the computationally-enriched biology curriculum enhanced students’ ability to identify the simplifications made by a model.