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Life, The Final Frontier

A Case Study on the Characteristics of Life

Co Authors:

William D. Rogers
Department of Biology
Ball State University

Thomas Horvath
Biology Department
SUNY College at Oneonta


Designed for high school and college-level introductory biology courses, the goal of this "clicker case" is to get students to think about what it means for something to be alive by defining the characteristics of living organisms and applying these to living, nonliving, and previously living objects. The case does this within the framework of a fictional scenario in which the President of the United States must decide whether to announce that NASA has discovered extraterrestrial life. However, NASA is not sure how to define their discovery. The case combines the use of student personal response systems (clickers) with case teaching methods and formats. It is presented in class using a series of PowerPoint slides (~1MB) punctuated by questions (called "clicker questions") that students respond to before moving on to the next slide. The case could be adapted and used without these technologies.

  • List and define with examples the necessary characteristics of life.
  • Categorize objects as alive or not alive.
  • Generate an example of why it is important to be able to determine if something is alive or represents life.
  • Understand that many nonliving things can show several characteristics of living things, but cannot show them all.
  • Be introduced to various areas of study within biology.
  • Begin to realize that biological "facts" can change as scientists learn more.
Keywords: Definition of life; evidence of life; characteristics of life
Topical Area: N/A
Educational Level: High school, Undergraduate lower division
Formats: PDF, PowerPoint
Type/Method: Clicker, Dilemma/Decision, Interrupted
Language: English
Subject Headings: Biology (General)   Science (General)  
Date Posted: 11/26/08
Date Modified: N/A
Copyright: Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

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We used this case with great success in my Sophomore Biology and Junior Honors Biology classes; the discussions were fantastic. I paired it with the "checks" activity from Indiana University's website for our third day of class discussion. Together, they provided an interesting view of how science works. Here's the link to the activity:

Thanks for the great work!

Bethany Dixon
Western Sierra Collegiate Academy
Rocklin, CA

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