Permafrost is any soil or surface deposit in an Arctic or alpine region at some depth below the surface at which the temperature has remained below zero degrees Celsius (32 degrees Fahrenheit) continuously for a long period of time. The amount of carbon dioxide and methane stored in permafrost is nearly twice the amount in the atmosphere and, as the ice melts, these greenhouse gases escape, warming the planet. Locally, the land surface is disturbed, the water cycle changes, and ecosystems are disrupted. Changes to the atmosphere are invisible and permafrost forms in distant polar regions, so it is difficult for people to see changes that result from melting permafrost. Building a model in the classroom connects students with a visual representation of permafrost and provides observations of physical and thermal changes. This article describes a lesson in which students begin by examining why the melting of permafrost matters. Next, they construct a physical model of permafrost in the classroom that provides insights through observation, data collection, and comparison to authentic permafrost data. In addition to constructing a realistic physical model, students use technology to measure temperature. The lesson concludes with students interpreting data from Alaska to identify patterns and estimate the rate of change.