Using Student-Created Metaphors to Assess Comprehension of Geologic Time

Roger Steinberg
Department of Natural Sciences, Del Mar College
At Del Mar College, we are now officially assessing the comprehension of the immensity of geologic time by our Historical Geology students. This is one of six Geology Program student learning outcomes that we assess via WEAVEonline.

To demonstrate their comprehension of the immensity of geologic time, students create and discuss, in a written report, their own metaphor for geologic time. The objectives of this student learning outcome are the following:
  1. Students will develop a metaphor for geologic time.
  2. Students will calculate the ratio or percentage, relative to the age of the Earth, of the age of 17 important events in geologic history that are given with the instructions for the project.
  3. Students will compose a written description or narrative of their metaphor, explaining why they chose it, and quantitatively compare the list of important events in geologic history to their metaphor.
  4. Finally, students will evaluate the effectiveness of their metaphor in comprehending geologic time.
I've given this assignment to students off and on for a number of years, sometimes making it a requirement, sometimes keeping it optional, with varying levels of student participation and success. This year, we are making it part of our course assessment.

(The idea of using student created metaphors to assist in comprehension of geologic time is borrowed from a paper by Scott David Ritger and Robert Hays Cummins that appeared in the Journal of Geological Education, v.39, p.9-11, 1991.)

What learning is this evaluation activity designed to assess?

The measure for this objective is a written report, graded by the instructor of the class with the following rubric:
  • Creativity -- 20%
  • Narrative -- 50%
  • Mathematical calculations -- 20%
  • Evaluation of metaphor -- 10%
  • Extra credit for visual aid --10%
Our target is fairly simple: 70% of students in Earth History (GEOL 1404) (our Historical Geology class) will score at least 70% on this exercise.

What is the nature of the teaching/learning situation for which your evaluation has been designed?

This is a recent addition to the WEAVEonline assessment of our Geology students. We will assign this project fairly early in the semester, after Historical Geology students have mastered the concepts of relative and actual age-dating, and have learned about the Geologic Time Scale and its historical development. This gives students most of the semester to work on the project.

This is a stand-alone project used in course and student-learning assessment. We will not evaluate every student, but will select one or more classes for evaluation each semester or academic year.

What advice would you give others using this evaluation?

  • Should be mandatory, not optional
  • Assign early in the semester
  • Supply students with a detailed example, including one possible way of doing the calculations
  • If desired, an oral presentation component could be added

Are there particular things about this evaluation that you would like to discuss with the workshop participants? Particular aspects on which you would like feedback?

Evaluation Materials