Relative/Absolute Dating and Fossils:
Units of Study: An Overview
Brenda Shafer
8th Grade Earth and Space Science
Gray Middle School
Union, Kentucky
Brenda.shafer@boone.kyschools.us
UNIT DESCRIPTION:
The purpose of teaching fossils and relative dating are to facilitate the
student’s understanding of how fossils are formed, how time is measured on a
geologic scale, and how dating and fossils are inter-related.
BIG IDEAS OF SCIENCE:
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Physical evidence, such as fossils and radio isotopic dating, provide
evidence for the Earth’s system’s evolution and development.
Earth’s rocks and other materials provide a record of its history.
Fossils are the preserved evidence of ancient life.
Earth’s materials may take many different forms as they cycle through
the geosphere.
ENDURING UNDERSTANDINGS FOR THE UNIT:
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Students will research and evaluate the geological dating techniques that
are used to determine the accepted age of the Earth.
Students will identify a variety of landforms on the Earth’s surface that
have undergone changes (both fast and slow) and investigate the forces
responsible for those changes
Students will identify the types of fossils, how they are formed, and their
use in understanding geological time.
ESSENTIAL QUESTIONS FOR THE UNIT:
1) What are the 8 types of fossils? (trace, petrified, mold, cast, frozen,
mummified, tar, and amber)
2) Which types of fossils do not preserve the original organism and why?
3) Explain how fossils can be used to study changes in the environment
and/or the organism they come from.
4) What is an index fossil and how is it used?
5) Explain how relative dating is used.
6) How is the geologic column used to date rocks and fossils?
7) What events and features disrupt the rock layers?
8) How are physical features used to determine relative dating?
9) Explain how radioactive decay occurs.
10)
Name several types of radiometric dating.
11)
How does radioactive decay relate to radiometric dating?
12)
What are two ways to do absolute dating without specialized
equipment?
KNOWLEDGE AND SKILLS:
FOSSILS
 The student will be able to name at least 8 types of fossils and explain
their formation.
 The student will be able to discern which fossils preserve the original
organisms and which ones do not and be able to explain why.
 The student will be able to determine which type of rock best preserves
fossils and why.
 The student will demonstrate how fossils can be used to determine
changes in environments and in the organisms the fossils came from.
 The student will describe an index fossil and how it is used for dating.
RELATIVE DATING
o The student will be able to demonstrate an understanding of a geologic
column to date fossils and rock layers.
o The student will be able to explain how relative dating is used in geology.
o The student will be able to explain the rule of superposition.
o The student will be able to identify events and disruptions to rock layers
when provided with a cross section of disturbed rock layers.
ABSOLUTE DATING
 The student will be able to explain how radioactive decay occurs.
 The student will be able to name two methods of absolute dating that can
be done without specialized equipment.
 The student will be able to explain at least two types of radiometric
dating.
 The student will be able to explain the relationship between radioactive
decay and radiometric dating.
MISUNDERSTANDINGS BY STUDENT:
 Petrifying is not the organism turning into stone by magic.
 Mummification in Egypt among the pharaohs is not the same as Mother
Nature’s mummification process that forms fossils.
 Radioactive decay does not mean you will glow in the dark due to
radiation exposure or that the decay will stink.
 Relative dating has nothing to do with people dating each other.
GRASP
G – The goal is to enable students to associate rocks and fossils as tools for
dating geologic history through relative and absolute dating.
R – You are an amateur geologist
A – The audience will be a primary class of science students at Mann
Elementary.
S – You have been asked by a primary teacher at Mann Elementary to present
three of the local Boone County fossils to their students and to discuss the
ages of the fossils and surrounding rock layers in Boone County along the I-75
or I-275 corridor.
P – The students will develop a power point presentation that includes the
three fossils, photos of the surrounding rock layers, and a picture of what
Boone County looked like during the life time of the fossils and rocks. Actual
fossil specimens will also be available for the elementary students.
S – Standards for the product will include:
1.
2.
3.
4.
5.
6.
Manuscript writing for the elementary student to read.
Easy to understand language and definitions
Color and sound where applicable in the power point.
Easy to see photos that large enough to see some details.
Clear photos of at least 5 sections of rock layers from the interstate.
There should be at least 6 of each of the three fossil samples to pass
around the room.
7. One book that the students would find in the public library and one
from their school library about fossils and geologic time changes. (Try
to avoid dinosaurs)
8. Able to answer questions of students with confidence and ease.
9. A poster to leave in the room with the students for their future
reference and/or enjoyment of fossils and rock layer study.
PRECONCEPTIONS SURVEY:
I would accomplish this by giving the school system’s county question
bank for earth science skills from previous grade levels, plus some of my own
questions.
QUIZZES, TESTS, AND ACADEMIC PROMPTS:
Quizzes for reading assignments and from the previous day’s material
will be possible quiz material.
Tests will consist of about 10-15 multiple choice and/or fill-in-the blank
questions, followed by one or two open response questions.
Academic prompts will include previous content covered in 6th and 7th
grade, as well as real life experiences they may have had. Some kids are into
collecting fossils or have been on fossil digs at local museums.
OTHER ASSESSMENT EVIDENCE:
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Daily bell ringer responses/question of the day
Class discussion/participation
Video participation/discussion
Fossil identification lab
Cartoon Group participation and product completion
Exit Slips
Center activities
 Computer lab web searches or guided activities
 Inquiry activities
W H E R E T O:
W – Students will be given a study guide (similar to the model from Dr. Wong’s
book, First Day of School). This guide will provide what we will study, what is
expected from them, and what the major assignments will be for this unit(s).
H – The hook will be my bulletin board of fossils, rock cross sections, and
vocabulary for the unit(s) we are studying.
E – Events that will be used are fossil finding within our room using a large
assortment of rocks and local fossil identification sheets. A selection of fossil
resource books and charts, enlarged photos of rock layers from the
surrounding area, a slice of a tree with a question asking how old was the tree,
and a guess speaker from a local fossil organization.
R – The fossils will be displayed throughout the study in display cases or in
boxes on the floor for the students to access when they have an opportunity.
Resource books will be accessible at all times. The daily bell ringer will be
discussed as a whole group or in pods. Opportunity to bring in fossils to be
identified using resource books, peers, or teacher will be open through the rest
of the time they are in my classroom for the year.
E – A rubric will be provided for the performance activity and for many of the
other areas that are graded or assessed. Quizzes will be in percents.
T – This will accomplished through formative assessment, altered work
assignment, pairing with another student, teacher willingness to entertain
student ideas and suggestions for a different or enhanced performance activity,
or ways to change the activity to make it more meaningful to the student.
O – I will organize by breaking the units into bite sized lessons that build upon
the preceding lesson, review the preceding lesson, and then add to the material
covered. Learning experiences will try to incorporate and combine the learning
modalities of students using visual, tactile, auditory, and kinesthetic type of
lessons and materials.