Relative Dating Lesson Plan

Instructor: John Hamilton

John has tutored algebra and SAT Prep and has a B.A. degree with a major in psychology and a minor in mathematics from Christopher Newport University.

Educate your students about relative dating with this lesson plan. They will view two video lessons, take two related quizzes, and participate in two activities that will help to reinforce newly-learned material.

Learning Objectives

After reviewing this lesson, your students will be able to:

  • Describe the nature of inclusions and unconformities
  • Explain what relative dating is as well as some of its related principles
  • Give several examples of index fossils and describe how they are used


1 - 1.5 Hours

Curriculum Standards


Cite specific textual evidence to support analysis of science and technical texts, attending to the precise details of explanations or descriptions.


Determine the central ideas or conclusions of a text; trace the text's explanation or depiction of a complex process, phenomenon, or concept; provide an accurate summary of the text.


Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 9-10 texts and topics.


Key Vocabulary

  • Assemblage
  • Earthquake
  • Fault lines
  • Geologic time
  • Grand Unconformity
  • Inclusions
  • Outcrop
  • Principal of Fossil Succession
  • Rock strata
  • Stratigraphic succession
  • Unconformities
  • William Smith
  • Law of Superposition


  • Inform your students they will be studying the scientific concept of relative dating.
  • Display an image of William Smith.
  • Ask your students if anyone is familiar with Smith's work or the method of relative dating.
  • Review the key vocabulary terms.

Lesson One

  • Play the video lesson What is Relative Dating? - Law of Superposition, Principles of Original Horizontality & Cross-Cutting Relationships and pause for the first time at 1:05.
    • What are the two ways geologists determine the age of rocks?
    • Which is more accurate?
    • Can relative dating establish exact age?
    • What is stratigraphic succession?
  • Now restart the video and pause this time at 1:50.
    • What does the Principle of Original Horizontality mean?
    • To what type of rocks does it apply?
    • Of what are sedimentary rocks composed?
    • How do these rocks form over time?
  • Next restart the video and pause again at 3:40.
    • What does the Law of Superposition state?
    • Are the oldest rock layers toward the bottom or the top?
    • What if a rock is tilted?
  • Again restart the video and pause at 4:43.
    • What does the Principle of Cross-Cutting Relationships say?
    • Does this concept apply to fault lines as well?
  • Restart the video and pause for a final time at 7:12.
    • What are inclusions?
    • What are unconformities?
    • What is the Great Unconformity?
    • How are its two types of rock different?
    • How do scientists establish the relative dates of its rocks?
  • Finally, play the 'Lesson Summary', recap the complete video lesson, and answer any relevant student questions.
  • Have your students take the lesson quiz to display their comprehension of the new material.

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