Mineral Cleavage CogSketch geoscience worksheet

Bridget Garnier
,
University of Wisconsin-Madison

Summary

Sketching activity that uses a sketch-understanding program, CogSketch. Students work through a series of tasks to understand the mineral cleavage of mica and amphibole. Students sketch the "cleavage planes" through common objects, the cleavage planes in the atomic structure of mica and amphibole, and match atomic structures to hand samples with visible cleavage planes.

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Context

Audience

Undergraduate introductory course in geoscience

Skills and concepts that students must have mastered

Students should be introduced to mineral cleavage

How the activity is situated in the course

We have used this activity as a homework assignment after the topic is introduced in lecture and reading, but it could also be used in class, in lab, or as group work.

Goals

Content/concepts goals for this activity

Students will understand the relationship between atomic structure and mineral cleavage

Students will be able to identify cleavage planes in diagrams of micas and amphiboles

Higher order thinking skills goals for this activity

Penetrative thinking: Imagining the interior of an object - in this case, a mineral

Disembedding: identifying the salient features in a visually complex image - in this case, finding the weak links in the atomic structure of a mineral

Other skills goals for this activity

Description of the activity/assignment

This worksheet focuses on understanding mineral cleavage, what controls mineral cleavage, and how cleavage at the atomic scale correlates to cleavage at the macroscopic scale. Students complete 3 tasks in this worksheet, focused on the cleavage of mica and amphibole. The first task focuses on common objects that have similar "cleavage" to mica (a stack of wood) and amphibole (snake scales). Students sketch the cleavage planes on the stack of wood and snake scales. The second task has students sketch cleavage planes onto images of the atomic structure of mica and amphibole with weak bonds highlighted in red. The last task has students match the atomic structure images of mica and amphibole to hand samples that clearly show the orientation of cleavage. The aim of this progression is to link something the students know (common objects) to something they don't know (atomic structure and hand samples), while keeping the geometry of cleavage planes the same. After all tasks are complete, students answer 5 multiple-choice questions.

This worksheet uses the sketch-understanding program with built-in tutor: CogSketch. Therefore, students, instructors, and/or institution computer labs need to download the program from here: http://www.qrg.northwestern.edu/software/cogsketch/. At any point during the worksheet, students can click the FEEDBACK button and their sketch is compared to the solution image. The built-in tutor identifies any discrepancies and reports pre-written feedback to help the student correct their sketch until they are done with the activity. Once worksheets are emailed to the instructor, worksheets can be batch graded and easily evaluated. This program allows instructors to assign sketching activities that require very little time commitment. Instead, the built-in tutor provides feedback whenever the student requests, without the presence of the instructor. More information on using the program and the activity is in the Instructor's Notes.

We have developed approximately two dozen introductory geoscience worksheets using this program. Each worksheet has a background image and instructions for a sketching task. You can find additional worksheets by searching for "CogSketch" using the search box at the top of this page. We expect to have uploaded all of them by the end of the summer of 2016.

Determining whether students have met the goals

CogSketch has a gradebook feature that allows instructors to batch grade worksheets using the defined rubric in the worksheet. Once graded, instructors can also open all the sketches and evaluate student work. Instructions are given in the Instructor's Notes.

More information about assessment tools and techniques.

Teaching materials and tips

Other Materials

Supporting references/URLs