I.C. Slingerland contributed to the TUDelft-MUDE/book repository by correcting a mathematical error in the Divergence Theorem exercise section. Using Jupyter Notebook and leveraging expertise in physics and technical writing, Slingerland replaced an incorrect surface integral over volume with the appropriate volume integral, ensuring the exercise accurately reflected the Divergence Theorem. The update was implemented as a focused, well-documented patch, maintaining codebase stability and clarity for future contributors. This change improved the accuracy of learner materials and reduced potential confusion for students, demonstrating careful attention to mathematical detail and effective communication of technical concepts within educational content.