Mass Extinctions and the Fossil Record

Elizabeth Heise
University of Texas at Brownsville
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This is a writing assignment for historical geology. Students submit online and peer-review their work.

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Undergraduate gen-ed historical geology course. This could be easily adapted for an upper-level course by changing the level of detail in the writing prompt and modifying the calibration essays.

Skills and concepts that students must have mastered

They need limited knowledge of mass extinctions and their causes.

How the activity is situated in the course

Towards the last 3rd of the semester as we approach the Mesozoic. This assignment is used to introduce mass extinctions outside of class time.


Content/concepts goals for this activity

Students will explore different mass extinctions in the geologic record. Students will compare two mass extinction events.

Higher order thinking skills goals for this activity

Students use critical thinking skills to evaluate writing. They also use communication and practice their writing skills. They must collect information from a variety of sources and synthesize it into an essay.

Other skills goals for this activity

Other skills that they use are computer skills and limited html coding.This is often the first time a student has used html coding.

Description of the activity/assignment

Students write a short essay that compares the Permo-Triassic (Permo is short for Permian) mass extinction with the Cretaceous-Tertiary (Tertiary is the beginning of the Cenozoic) mass extinction. The use online resources and their textbooks as source material for their essay.

Students must include information about the magnitude of the extinction events. Additionally students describe the groups of organisms that were impacted by the event.

Students discuss the cause(s) of each the extinction event and compare the different causes. They explain how the cause impacted the different groups of organisms or why those particular groups were impacted.

The discussion must include some of the organisms that never recovered from the extinction.

Determining whether students have met the goals

The Calibrated Peer Review software guides students through a multi-phase peer review process. First they review 3 calibration essays written by the instructor - examples of a very good, average and weak essay. They use a rubric to score the example essays. The software compares their scoring with the instructor's key to determine the "quality" of reviewer. If they do not "master" the calibrations, they are sent back to try again to hone their reviewing skills. This phase is worth part of their overall score.

Students then peer-review the submissions of 3 of their peers. They use the same rubric used in the calibration phase. Additionally they are asked to provide feedback for the components of the rubric. These reviews are compared by the software against the reviews of the other peers who reviewed the same essays to determine if the quality of the reviews. This is also worth part of their overall score.

The students then do a self-assessment of their submission using the same rubric. Their self-assessment is compared by the software against the weighted assessment by their peers to determine the quality of the self-assessment. The individual reviews are weighted based on the "quality" of the reviewer as was established in the first reviews. This self-assessment is another part of their overall score.

The last part of the overall score is the weighted average of the peers score for the original submission.

Students get feedback on their essay from their peers.

Faculty set the percentages for each of the components in the review process. They also set the tolerance ranges for if the reviews are close enough for full credit. Additionally, faculty can override any of the scoring on any part of the assignment.

More information about assessment tools and techniques.

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