3. Student Learning Map

  • Topic:05- The History of the Earth
  • Subject(s):Science
  • Days:12
  • Grade(s):6
Key Learning:

Thousands of layers of sedimentary rock confirm the long history of the changing surface of the Earth and the changing life forms whose remains are found in those successive layers.

Unit Essential Question(s):

What are the most effective ways to determine the relative and absolute age of the Earth?


Fossil Record

LEQ: Number 1

  • Describe some of the various types of fossils including casts and molds, permineralized, carbon film, mummified and trace fossils.
  • Recognize that fossils form in sedimentary rocks. Explain that the conditions must be absolutely perfect in order for a fossil to form.
  • Emphasize that the probability of specimens of any species of organisms surviving is small-soft body parts are eaten or decomposed, and hard parts are crushed or dissolved.
  • Discuss how fossils can be used to explain changes in Earth's life forms and climate over long periods of time. The fossil record provides snapshots of the past. Although the fossil record is not complete, fossil evidence clearly shows that life is old and has changed over time (evolved).
  • Explain how knowledge gained from the age of the rocks where the fossils are found provides us with the sequence of change that has encompassed the history of life. Samples of the same fossil species or related species can be placed into the order in time that they lived in order to understand the evolutionary history of a group.
  • Discuss how when scientists examine all of the organisms that come from sequentially ordered fossil beds, they can develop temporal maps and scenarios of the changes that have taken place in ecological communities.
  • Discuss how scientific knowledge changes over time as new fossils are discovered.
  • Recognize that fossil evidence is used to support several scientific theories (the theory of evolution and the theory of plate tectonics). Remind students that a theory is not an opinion. A theory is based on empirical evidence and can be altered as new evidence is discovered. Do not cover the basics of either theory at this time. The theory of evolution will be taught in 7th grade. The theory of plate tectonics will be taught in the next unit.
  • LEQ: Number 2

  • HOTS: Deductive Reasoning could be used to demonstrate the ET LEQ.
  • Concept:

    Geologic Time

    LEQ: Number 1

  • Discuss how geologic time can be estimated by observing rock sequences and using fossils to correlate the sequences at various locations.
  • Explain that if a scientist knows the age of a certan type of fossil, then the rock that fossil is found in must have formed at the same time.
  • Recognize that fossils found underneath other fossils tend to be older. More recently deposited rock layers are more likely to contain fossils resembling existing species.
  • Identify the methods used for determining the age of rocks and fossils including radioactive dating, radiocarbon dating and relative dating techniques.
  • Explain that scientists use the Law of Superposition to determine the order of events that have occurred within an area (relative dating).
  • Scientists can also use certain fossils to determine the approximate age of the rock (index fossils).
  • Use visual diagrams to show the concept of a half-life and explain how knowing the half-life of an isotope scientists can use it to determine the numerical age of a rock or fossil. Apply the use of half-life to radiometric and radiocarbon dating.
  • LEQ: Number 2

  • HOTS: Deductive reasoning or error analysis could be used to support the ET LEQ.
  • Concept:
    Lesson Essential Question(s):

    What can we learn from the fossil record?


    How does the discovery of a new fossil provide evidence for how life has changed over time? (deductive reasoning)

    Lesson Essential Question(s):

    What similarities and differences exist between absolute and relative dating?


    How do the Law of Superposition and radioactive dating work together to help scientists determine the age of the Earth? (deductive reasoning or error analysis)

    Lesson Essential Question(s):
    Additional Information:

    The asterisk (*) next to the vocabulary terms above indicates essential FCAT vocabulary.

    Suggested Resources-

    Glencoe Earth Science program, classroom models, timeline activity, fossil lab, lab write-up template, the Internet and Unitedstreaming.

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    Acquisition Lesson:

    Extending Thinking Lesson:

    Vocabulary Report

    • absolute age -

      Age, in years, of a rock or other object; can be determined by using properties of the atoms that make up materials.

    • law of superposition -

      States that in undisturbed rock layers, the oldest rocks are on the bottom and the rocks become progressively younger toward the top.

    • index fossil -

      Remains of species that existed on Earth for a relatively short period of time, were abundant and widespread geographically, and can be used by geologists to assign the ages of rock layers.

    • radioactive dating (radiometric) -

      Process used to calculate the absolute age of rock by measuring the ratio of parent isotope to daughter product in a mineral and knowing the half-life of the parent.

    • relative age -

      The age of something compared with other things.

    • half-life -

      The time it takes for half the atoms of an isotope to decay.

    • *fossil -

      Nonrenewable energy resource, such as oil and coal, formed over millions of years from the remains of dead plants and other organisms.

    • geologic time scale -

      Division of Earth's history into time units based largely on the types of life forms that lived only during certain periods.