Connecting magma formation, origin of crust, and the meaning behind igneous rocks using research-based diagrams, analogies, and games in physical geology

Thursday 1:30pm-1:50pm Weeks Geo: 140
Teaching Demo


Andrea Bair, Delta College


I will demonstrate the set-up and sequence of the activity, and all materials will be available. Interactive engagement pedagogy is emphasized and will be modeled, including peer learning, in-class questions for use with clickers or other instant feedback methods, and other classroom assessment techniques to probe student understanding. Modifications for visually impaired students are included in the presentation. Options for "clicker"-based games, a card sort "melting" game, and laboratory activities and scientific analysis and writing activities that extend the module will be presented (time allowing!)


This activity aims to:

  1. dispel common misconceptions about the origin of magma (i.e., from a liquid layer of Earth),
  2. promote understanding of the processes of magma generation,
  3. help students see igneous rocks as products of their formation and connected to plate tectonic processes,
  4. promote expert-like use and understanding of graphs and other diagrammatic representations,
  5. help students connect concepts and phenomena at different spatial and temporal scales.

This activity centers on common images used in teaching students about magma generation and plate tectonic processes (cross sections and graphs) specifically modified to avoid common student misconceptions. Connections between processes are emphasized.

Outcomes include:
  1. Identify which layers of Earth magma comes from, and the nature of magma areas in those layers.
  2. Explain how partial melting influences magma composition. List and describe the three main mechanisms for melting rocks.
  3. Draw pressure-temperature graphs for each kind of melting.
  4. Be able to explain how each igneous rock forms including: source rock composition and layer of Earth, plate boundary (or boundaries) that most likely are the location for melting that layer of Earth, the mechanism(s) for melting that produced the magma, and where the rock formed.


This activity is designed primarily for use in introductory geology courses, but I have also used a modified, much shorter version in other introductory level non-major geology courses. I use this activity after modules on Earth layers, plate tectonics, minerals, and after students have completed a laboratory activity on identifying igneous rocks. Students should be familiar with names and properties of the compositional and mechanical layers of Earth, major types of igneous rocks, and basic processes and surfaces features of convergent and divergent plate boundaries prior to this activity.

Why It Works

This activity targets common student misconceptions with a greater effectiveness than other activities and approaches I have used. Students are highly engaged, and are practicing geological problem-solving strategies when participating. Student peer discussions are high-quality and conceptually-focused. Many students mention this activity as helping them see that "rocks are not just rocks"; rocks are not simply objects, but contain information that tells the story of their formation, if you know how to read it.