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Time and Earth History Socratic Questions

Created by Robert Walter and Dorothy Merritts, Franklin & Marshall College (robert.walter@fandm.edu, dorothy.merritts@fandm.edu)
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This material is replicated on a number of sites as part of the SERC Pedagogic Service Project


Questions regarding Time and Earth History are arranged in sequence for a session of Socratic questioning.

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Learning Goals

To develop a sense of geologic ("deep") time and the ways in which Earth scientists construct the geologic time scale. To understand the major events that shaped Earth, including the origin and evolution of its lithosphere, atmosphere, and hydrosphere. To establish a context for understanding the origin and evolution of life on Earth.

Context for Use

This example is suitable for in-class use during a lecture period. No equipment is required unless the instructor wishes to use supplemental images. Excellent images and other educational resources are available at numerous web sites, which add significant impact to this topic during class discussions. Some examples are given below in References and Resources.

Teaching Materials

Sample questions arranged in sequence for Socratic questioning regarding Earth History and Time:

  • What is time and how is it measured?
  • Why might one conclude that time is an essential physical law of the Universe?
  • What is geologic time and why is it often referred to as "deep time"? How did the early geologists measure deep time?
  • How did the discovery of radioactivity enable the direct measurement of deep time?
  • How old is Earth and how do we know this?
  • Where did Earth's water come from? When did it first accumulate in abundance?
  • When did Earth's atmosphere form? What is the composition of the atmosphere today and how is it different from the atmosphere during the early stages of Earth history?
  • When did oxygen accumulate in abundance in Earth's atmosphere? What is the evidence?
  • What was the Cambrian Explosion and what was its significance?
  • How much time passed from the formation of Earth until life emerged on land? What is the percentage of this time compared to Earth's age? Devise an analogy to express this percentage?

  • The above plus other Socratic questions, with general answers for most, can be downloaded as a PDF file from Time and Earth History Questions and Answers (Microsoft Word 36kB Jul31 03).

    Teaching Notes and Tips

    Tips: As in all Socratic questioning, give students time to reflect before answering questions, and make an effort to call on different students throughout the class period. Let students know at the beginning of class whether or not you will call on students randomly, or ask for hands to be raised, or both.

    To explore the questions on Earth History and Time fully, allow at least a full class period of 50 to 90 minutes.


    Many simple details can cause problems when using Socratic questioning. For example, students might feel that they never are given quite enough time to reflect on the answer before called upon. They might not be able to hear some of the other students' answers, especially in a large classroom. They might find it very challenging to take notes during the questioning and response session, and at least will find it more difficult to take notes than during a traditional lecture/chalk class.

    The best way to determine what problems are occurring is to give students a questionnaire after each of the first few classes in which the approach is tried. Ask students directly if they think that you are allowing sufficient time for reflection. Ask if they are concerned about hearing other students' responses, and so forth. Add one question that asks students to make note of any problems not referred to in the questionnaire.

    Each student should be able to answer any of the questions that was posed during the Socratic questioning session. A good way to assess what the students have learned from a Socratic questioning class is to give a short quiz in which several of the questions from the previous class are listed. This quiz can be given at the beginning of the next class period. If the class is large and grading frequent quizzes is too burdensome, the questions can be designed with multiple-choice answers.

    References and Resources

    Many excellent web sites exist that contain educational resources and imagery for teaching about Time and Earth History. Three good ones to begin with are: