In this activity, learners make a miniature greenhouse or "terrarium" to explore the greenhouse effect. Learners will first construct their model greenhouse using a clear, tall airtight container, potting soil, small plants, pebbles, and filtering charcoal. Then, learners will observe the terrarium closely for several days, record how the plants grow, and chart temperature readings inside and outside the container. Learners are encouraged to compare their findings with each other. This activity can be used to introduce learners to climate change issues.