In this math lesson, learners apply mathematical modeling to solve a real-world storage problem, in which a manufacturing company is given two options for storing oil barrels. These options include a square storage unit and a rectangular storage unit (twice the area of the square unit). Learners must decide which of the storage units will provide the most inexpensive space to store 125 containers. Learners use 35mm film canisters and paper mats to model storage arrangements for each unit. Learners find that the arrangement of the cylinders in the storage unit affects the cost. Learners work in small groups, collecting data, performing necessary computations, and constructing reasons for their unit selection.