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Igneous Rock Classification

This material was originally created for On the Cutting Edge: Professional Development for Geoscience Faculty
and is replicated here as part of the SERC Pedagogic Service.
John Brady, Smith College
Course: Petrology
10 students
The most effective way to develop geoscience skills in your students is to make opportunities for them to practice those skills. Although prior knowledge may be helpful in this exercise, it is not required.

The Activity

I give each small group of students about 25 igneous rock samples to examine. I ask them to organize the samples into groups and to be prepared to explain the reasoning behind their groupings. We then have a whole class discussion of the various classification schemes devised. Finally, I distribute the IUGS igneous rock classification scheme and we discuss its reasoning and use.