Learning Assessment #4 - Metamorphic Rocks

Leslie Reid1, Ben Cowie1, Michelle Speta2
,
1University of Calgary, 2University of Alberta

Summary

An in-class activity that tests students' understanding of metamorphic rocks and processes.

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Context

Audience

This activity was used in an introductory physical geology course that is also open to students in all faculties, and is a mandatory course for geoscience majors. No pre-requisite courses required. The course page is available at: http://serc.carleton.edu/NAGTWorkshops/coursedesign/goalsdb/65489.html

Skills and concepts that students must have mastered

Students must be familiar with the basic concepts of metamorphic rocks and processes, including: metamorphic grade, protoliths, regional vs. contact metamorphism and relevant minerals and textures (i.e. types of foliation).

How the activity is situated in the course

This assignment is part of a series of in-class activities known as learning assessments. However, it would also be suitable for use as a stand-alone exercise. Students are strongly encouraged to work in groups, however each student must submit their own assignment. Learning assessments are all "open book" and students are encouraged to use their textbooks and other external resources to help them complete their assignments.

Goals

Content/concepts goals for this activity

Developing an in-depth understanding of metamorphic rocks and the physical processes that drive metamorphism, with the goal of being able to discuss the metamorphic history of a sequence of rocks including associated tectonic settings, physical processes (e.g. burial, uplift) and mineral-scale processes (recrystallization, neocrystallization etc.). This learning assessment also tests student's understanding the relationship between protolith lithology and metamorphic mineral assemblage.

Higher order thinking skills goals for this activity

Synthesis of ideas (e.g. what kinds of tectonic settings drive regional metamorphism? How are different metamorphic zones related to each other?)

Other skills goals for this activity

Writing, working in groups, using external resources (e.g. internet, textbooks)

Description of the activity/assignment

In Part 1 of this activity, students are provided with a map of metamorphic zones, where they are asked to label each zone with the appropriate type of metamorphism (regional or contact) and grade (high, intermediate, low). Helpful mineral assemblage and P-T diagrams are provided (From Earth: Portrait of a Planet 4th edition by Stephan Marshak. Copyright © 2012, 2008, 2005, 2001 by W.W. Norton & Company, Inc. Used by permission of W. W. Norton & Company, Inc.).

In Part 2, students must provide the type of foliation that occurs in each regional metamorphic zone (from chlorite to sillimanite), as well provide two other metamorphic minerals that would be found in each zone, on the basis of a shale protolith.

Part 3 asks students to describe the metamorphic history of the area shown on the map, starting from the tectonic setting in which metamorphism would have been initiated to how the rocks got exposed at the surface today. Details such as associated igneous processes, depth of burial, mineral-scale processes etc. must also be included.

Determining whether students have met the goals

Learning assessments are returned to students during a review period where the instructor devotes a class to going over the activity and explaining common errors. Learning assessments are graded using a checklist-style rubric which is a more detailed version of checklist provided to students with the assignment. Using the graded checklist as a guide, students complete a feedback activity during the review period, which gives them an opportunity to reflect on their understanding of the concepts covered in the learning assessment. The feedback activities are submitted, allowing the instructor to determine whether students have met the goals of the activity.

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