Popping Popcorn Kernels: Expanding Relevance with Linear Thinking

Graphing skills and an understanding of linear relationships are developed in the context of popping of individual popcorn kernels. Introductory-level chemistry students determine mass changes as the result of popping along with the volume and density of the popcorn flakes produced. Graphs of mass and volume data and a digital picture of the popcorn flakes are used to test two hypotheses and their corollary: (i) flake and kernel masses are directly proportional, (ii) flake volume and kernel mass are directly proportional, and the corollary, flake density is a constant. The first hypothesis is confirmed. However, variability in flake density is a common result, apparently disconfirming the second hypothesis and the corollary. Thoughtful attention to the current understanding of the popping mechanism is required to account for the results.