Yakima WATERS Mini Lesson
Toilet Paper Geologic Timeline
Targets and Assessment
WA Science Standards Addressed:
 6-8 ES3B Earth History: Thousands of layers of sedimentary
rock provide evidence that allows us to determine the age of
Earth's changing surface and to estimate the age of fossils
found in the rocks.
 6-8 INQE- Model: Models are used to represent objects, events,
systems, and processes. Models can be used to test hypotheses
and better understand phenomena, but they have limitations.
Assessments:
 Grade worksheet
 Grade students on group cooperation and participation
Lesson Parameters
Content Area: Geology
Overview: Students explore deep time by
reconstructing Earth’s geologic history on a roll
of toilet paper.
Grade Level: 6-8
Suggested Time: Two 50 minute class periods
Special Materials:
 Computer access for entire class
 150 meter tape
 1000 sheet roll of toilet paper
Learning Outcomes:
Knowledge:
 Student can explain that the age of landforms are estimated by: studying the number and thickness of
rock/sedimentary layers; radiocarbon and isotopic dating methods; and analysis of fossils found within
rock layers to determine the age of specific events in Earth’s history.
 Student recognizes that the events on the geologic timeline represent major physical and biological
changes.
 Student explains that the majority of the events that have been recorded occurred in the past billion
years and that those events are most abundant because they have not been eroded or buried by
physical changes in the environment.
Skill:
 Students will be able to work cooperatively in teams
 Students will be able to develop a model that represents Earth’s geologic history. Students can explore
a difficult concept, deep time, by placing key events on a smaller, more tangible scale (toilet paper
roll).
Science Concept Background: Implementation of this activity would be best after students have had
some exposure to Washington State standards:
EALR 4: Earth and Space Science. Big Idea: Earth History (ES3). Core Content: Evidence of Change
Or
EALR 4: Earth and Space Science. Big Idea: Earth Systems Structures and Processes (ES2). Core Content:
Cycles in Earth Systems
If they have not had lessons from these subject areas the content may be too difficult to jump into. In the
“Procedure” section below suggestions are made on how you can introduce geologic time and carry out the
toilet paper timeline activity with minimal background information.
The concept of deep time can be a difficult concept to understand. Earth is an estimated 4.6 billion years old,
a number that goes beyond the amount of time humans typically deal with (minutes, hours, days, months,
years and sometimes, hundreds of years). The geologic scale has been divided into time periods that frame
specific physical and biological changes that have occurred and been recorded in landforms and by fossils.
Refer to the attached “GSA Geologic Time Scale” for a detailed breakdown of the timeline. Also attached is a
detailed list (TP Geologic Timeline Conversions (Excel)) of major events that have occurred from 4.6 billion
years ago to the present, this list is not comprehensive but may include more topics than you want to address
in one lesson. The four major time divisions in the geologic time scale are eras, Cenozoic, Mesozoic, Paleozoic
and Precambrian, these time segments are illustrated and described in Step #2 of the “Procedure” section.
Materials:
For the teacher: attached documents to prep for and complete the lab:
 Geologic Timeline Events (Word Doc.)
 Geologic Timeline Worksheet (Word Doc.)
 TP Geologic Timeline Conversions (Excel)
For the class:
 One 1000 sheet roll of toilet paper (for the entire class)
 150 meter tape (you need it to cover ~102 meters total)
For student groups:
 Computers (students work in pairs or groups of three)
 1 Red, green, blue and black markers
o 1 marker is assigned per group, for larger classes you may need 2 of each color to double the
number of groups for the activity
Procedure:
In addition to the attached documents the following website is an excellent resource for developing a mini
lesson on geologic time and the history of Earth, or as suggested and utilized in this lesson plan, the students
can explore the student tutorial found on this website: “Exploration Through Time: Understanding Geologic
Time” http://www.ucmp.berkeley.edu/education/explorations/tours/geotime/index.html
Step 1:
Have students begin by pairing up on a computer to run through the following student tutorial:
“Exploration Through Time: Understanding Geologic Time”
http://www.ucmp.berkeley.edu/education/explorations/tours/geotime/index.html
Begin by clicking on “student start”
This tutorial provides an introduction to the geologic time scale and discusses the types of evidence that are
used to determine how old the earth is and the events that have occurred throughout geologic history. Allow
approximately 20 minutes to get through the program.
Step 2:
After the tutorial have the students return to their seats to discuss what they learned from the tutorial. A
couple of questions that may be helpful in getting a discussion started may be:
How old is the age of the earth?
What lines of evidence do geologists use to determine the age of the earth?
What are some of the different types of dating techniques?
Then segue into a brief lesson to prepare them for the toilet paper timeline. On the board draw a timeline
that includes the key time periods that are emphasized in the activity. Each time period will contain timecorrelated geologic events that are color coded by the eras listed below.
Present to 65 MYA (millions of years ago) = Cenozoic (blue)
65-250 MYA = Mesozoic (green)
250-540 MYA = Paleozoic (red)
540-4600 MYA = Precambrian (black)
Cenozoic
Mesozoic
Paleozoic
Precambrian
*This example is not to scale
Step 3:
Assign students to groups. For larger class sizes I recommend splitting the events from each era into 2 groups,
that way there are a total of 8 groups of ~4 or 5 students.
Note: The slips that contain each event are found in the Geologic Timeline Events Word Doc. The slips should
be cut and separated into their respective era-color-coded group. An explanation and description of the event
slips is provided within the document.
Each group will be responsible for placing the events they are given in the appropriate time place along the
toilet paper timeline. Explain that they will tape the event slip onto the side of the toilet paper roll and using
the appropriate era group color draw a line across the roll, marking the time in which the event occurred. For
example, if a group had the event “dinosaur extinction” they would use the color blue and label the toilet
paper roll at 143.57 cm (from the beginning/present day end of the roll) as 65 MYA.
Step 4:
Take the class to the location where the activity will be held. Have the students unroll the toilet paper making
sure that it stays in one piece. At the toilet paper is being unrolled the tape measure should also be laid out
next to it. The tape measure will help guide the students through the timeline. Once the roll and tape are in
place students can break into their groups and begin placing the event slips on the roll. The photo below gives
you an idea of how the toilet paper timeline will look.
Once they have finished, bring the group together and walk through geologic time together, discussing the
events that have occurred as a group and allowing time for any questions and/or observations that the class
may have. The attached timeline worksheet can be handed out after the activity as homework or be
completed in class to turn in for a grade.
Present Day
65 MYA
250 MYA
55 meters to
the end of the
toilet paper roll
(4600 MYA)
Extension(s):
I followed this lesson up by having the classes construct a regional geologic timeline that will be built upon
throughout the year. The regional timeline enables the class to learn about events that shaped the local
landscape. This follow-up also provided an opportunity for the students to construct a shorter geologic
timeline on a smaller scale.
Teaching Tips:
If you do not have access to computers you will need to develop a mini lesson introducing the age of the earth
and discuss the lines of evidence that scientists have used to determine the timing of specific events in
geologic history. The following webpage is a great resource that can help you develop a lesson:
University of California Museum of Paleontology, K-12 Teacher Resources (Includes “Explorations Through
Time”): http://www.ucmp.berkeley.edu/education/teachers.php
Make sure that you have a long enough space to unroll the entire roll of toilet paper (~335 ft). On a dry day,
outside will work but remember that the toilet paper is fragile and tears easily so you will need a relatively
smooth surface to lay it down.
2-ply toilet paper is also recommended for durability, if you kind find 1000 sheet 2-ply.
Author: Tabitha Trosper, Yakima WATERS Project, CWU, Fall 2010