This well-organized lab activity introduces earth science pupils to the greenhouse effect. They will set up two experiments to monitor temperatures in an open jar, a closed jar, and a closed jar containing water. Ideally, you would have small groups perform their own tests, but if you do not have enough jars with lids, they can be done as a whole-class demonstration. A full-page data table, empty graphs, and analysis questions are all provided to help learners process the data. The lesson would make a nice starting point for a unit that addresses global warming and climate change.