#794: Opening Black Boxes: Unpacking Blocks to Balance Usability and Expressiveness in Computational Modeling

Computational modeling is a key practice in STEM classrooms. Block-based, domain-specific programming environments have made this practice more accessible but may constrain what students can design compared to general-purpose languages. This paper introduces “block unpacking”—allowing high-level primitives to be opened, inspected, and modified—in a domain-specific modeling environment. We implemented this feature in a four-day lesson on eutrophication, in which high school students programmed computational models to represent interactions between algae, bacteria, fish, nutrients, and oxygen. We analyzed 36 interactions with six unpackable blocks across three modeling challenges, examining the computational complexity and scientific relevance of students’ modifications. We found that unpacking enabled students to modify high-level primitives, via parameter and code structure changes, to optimize models and articulate scientific reasoning. We discuss implications for the design of programming environments and instructional materials that aim to balance usability and expressiveness in computational modeling.