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MERLOT II


    

Peer Review


Patterns of Extinction

by David Espar
 

Ratings

Overall Rating:

Content Quality: 4 stars
Effectiveness: 4 stars
Ease of Use: 4.25 starsstar
Reviewed: Oct 27, 2013 by Biology Editorial Board
Overview: The patterns of extinction web page is a small portion of the larger PBS web site called the Evolution Library. The page introduces some of the concepts and big picture items in the extinction conversation. The material presented references “Evolutionary Biology, 3rd Edition, by Douglas J. Futuyma”.
Learning Goals: None stated.
Target Student Population: Majors or non-majors biology students.
Prerequisite Knowledge or Skills: Understanding of basic taxonomy (biological family) and basic graph reading skills. An understanding of Zoology and Geology would be helpful.
Type of Material: This page is mostly designed around text, but does include a graph and links to definitions. Links provided connect the user to video’s and other great materials.
Recommended Uses: Instructors could use this graph in class, or assign it to students with the background text.
Technical Requirements: Basic web navigation and computer literacy. Navigating to the other parts of the web site require video.

Evaluation and Observation

Content Quality

Rating: 4 stars
Strengths:
  • The graph is interesting, simple, visually appealing and contains useful information
  • The information in the accompanying text is accurate and helps create a context for the graph
  • Several links in the accompanying text define terms
Concerns:
  • The points on the graph are not explained in a caption or in the text
  • The treatment is general, and relatively superficial
  • The caption and accompanying text do not explain how to interpret the graph except in very general terms, and some graph symbols are left unexplained

Potential Effectiveness as a Teaching Tool

Rating: 4 stars
Strengths:
  • The graph provides an effective graphic for the pattern of mass extinctions
  • The text is easy to read and is simple enough for non biology majors
Concerns:
  • Some aspects of the graph remain obscure (such as the meaning of the points and the interpretation of red vs. black points, what the several best fit lines mean, etc.)
  • The accompanying text does not explain some aspects of the graph, such as the general decline over time in background extinction rates

Ease of Use for Both Students and Faculty

Rating: 4.25 stars
Strengths:
  • The graphic can be enlarged in a separate window and printed
  • All the in text links worked
Concerns:
  • Text-based links at the bottom of the page could be relocated to the top of the material or integrated in to the body of the text.
  • Evolutionary Library link could be larger.

Other Issues and Comments: The lack of an image or PowerPoint version of this graph is the main issue for instructor use in class. The PDF version created form the print window has extraneous material on it, and the graph is not sized to fill the page. If I were to use this graph in a PowerPoint or Keynote presentation, I would capture it, convert it to a JPEG and import it into the presentation. Instructors who want to use this graph should peruse it carefully: some aspects of the graph are not explained (the geological time units, the meaning of the several best fit lines, the data points). The graph will also likely prove difficult for some students as the biggest extinction events are not the ones with the highest peaks (in fact peak height is not a direct indication of the total extinction severity for each mass event).