Deep Thinking Over Geologic Time

Joanna Richison, Deborah Herrington, Stephen Mattox
Type Category
Instructional Materials
Unit , Map , Lesson/Lesson Plan
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be "fully aligned," the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.


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Deep Thinking Over Geologic Time is a seven-part unit consisting of hands on activities and graphical analysis designed to investigate the role of fossils and rock layers in determining the Earth’s age and geologic history. Individual lessons begin with an investigation of relative dating (Days 1 and 2) in which students apply the Laws of Superposition and Original Horizontality. On Day 2, students analyze a Stratigraphic Succession Map of Michigan.  To make this more relevant to their students, teachers may want to substitute a map of their own state. Next, students participate in a hands on activity using information from “Earth cups” to develop a relative biological timeline of Earth’s history. The unit then shifts into scientifically-based activities, tasking students with creating a 4.6 billion year biological timeline and investigating connections among the stratigraphic succession maps of several US national parks. Finally, students utilize the concept of index fossils in their analysis of a simple geologic timeline provided in their student guide. The authors estimate that the unit can be completed in seven class periods. A handout of fossils to complete the Day 4 activity, a student guide and teacher guide are included and can be found at . The authors include a lengthy list of supplies necessary to implement the unit; teachers should allow themselves adequate time to gather all materials.

Intended Audience

Educational Level
  • Middle School
  • Grade 8
  • Grade 7
  • Grade 6
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

Performance Expectations

MS-LS4-1 Analyze and interpret data for patterns in the fossil record that document the existence, diversity, extinction, and change of life forms throughout the history of life on Earth under the assumption that natural laws operate today as in the past.

Clarification Statement: Emphasis is on finding patterns of changes in the level of complexity of anatomical structures in organisms and the chronological order of fossil appearance in the rock layers.

Assessment Boundary: Assessment does not include the names of individual species or geological eras in the fossil record.

This resource is explicitly designed to build towards this performance expectation.

Comments about Including the Performance Expectation
Several of the activities in this unit deal with the existence, diversity, extinction, and change of life forms observed in the fossil record. Specifically, the Day 3 activity tasks students with using evidence gained through “Earth cups” to construct a relative geologic timeline. Students use the idea of existence and extinction when analyzing the patterns observed in their excavated evidence. On Day 6, students analyze a simplified time scale that delineates the appearance and extinction of index fossils.

MS-ESS1-4 Construct a scientific explanation based on evidence from rock strata for how the geologic time scale is used to organize Earth's 4.6-billion-year-old history.

Clarification Statement: Emphasis is on how analyses of rock formations and the fossils they contain are used to establish relative ages of major events in Earth’s history. Examples of Earth’s major events could range from being very recent (such as the last Ice Age or the earliest fossils of homo sapiens) to very old (such as the formation of Earth or the earliest evidence of life). Examples can include the formation of mountain chains and ocean basins, the evolution or extinction of particular living organisms, or significant volcanic eruptions.

Assessment Boundary: Assessment does not include recalling the names of specific periods or epochs and events within them.

This resource is explicitly designed to build towards this performance expectation.

Comments about Including the Performance Expectation
In this unit, students begin with activities designed to identify prior knowledge and then progress through hands on lab activities and analysis to build an understanding of the role that fossils and rock strata play in creating a geologic timeline. In particular, the activity for Day 5 requires students to match rock layers found in different National Parks. This activity supplies the evidence for the role of rock strata in organizing Earth’s history; however, the questions provided by the authors do not require students to construct a three dimensional explanation for this phenomena. Teachers will need to construct the writing prompts necessary to elicit the evidence of this learning. For example, teachers may ask students to analyze and cite evidence from the patterns they uncovered to explain how rock strata can be used to organize Earth’s history. Whole group discussion questions are included in the student guide which will provide additional assistance to students as they construct their explanations.

Science and Engineering Practices

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
Several lessons in the unit depend on either creating or analyzing graphical displays to identify spatial or temporal relationships. The construction of timelines on both Days 3 and 4 require that students obtain and organize information in order to create a temporal timeline of Earth’s history. Day 5’s activity requires that students analyze and recognize spatial relationships among succession maps of three National Parks in order to determine which park has the youngest or oldest set of rock sequences.

Disciplinary Core Ideas

This resource is explicitly designed to build towards this disciplinary core idea.

Comments about Including the Disciplinary Core Idea
The activities provided for the first four days of the unit introduce students to the concept of relative dating and the Laws of Original Horizontality and Superposition. The activity scheduled for Day 5 requires that students apply the knowledge from the previous days to analyze the rock succession record for three National Parks: Grand Canyon, Zion and Bryce. Through analysis of rock types, time periods and fossil diversity, students will be able to identify the oldest and youngest rock sequences in the strata record. This activity is the most complex one in the unit so teachers should carefully consider group composition in order to support struggling learners. The authors note that they lead a class discussion about the information contained in and organization of the chart itself. This will assist students in successfully completing this task.

This resource appears to be designed to build towards this disciplinary core idea, though the resource developer has not explicitly stated so.

Comments about Including the Disciplinary Core Idea
Throughout the unit, students investigate how fossils embedded in rock strata help to organize Earth’s history. On Day 3, students create a relative geologic timeline using information obtained from “Earth cups”. On Day 4, students are tasked with creating a timeline illustrating biological succession and evolution. In this activity, each specimen is assigned a single date for its appearance on Earth. Teachers should remind students that an organism exists on Earth over a period of time and overlaps among organisms can and do occur. The timeline provided for the activity on Day 6 illustrates time spans for index fossils.

Crosscutting Concepts

This resource appears to be designed to build towards this crosscutting concept, though the resource developer has not explicitly stated so.

Comments about Including the Crosscutting Concept
Throughout the unit, students are tasked with identifying patterns both in hands-on activities and in their analysis of charts and diagrams. They use these patterns to understand the role fossils and rock strata play in organizing Earth’s history.

Resource Quality

  • Alignment to the Dimensions of the NGSS: The three dimensions of NGSS are strongly embedded in the lessons of Deep Thinking Over Geologic Time, aiding students in investigating the phenomena of rock and fossil location in establishing a timeline of Earth’s history. Students are tasked with analyzing multiple data sources (Practice) looking for patterns (Crosscutting Concepts) that allow scientists to use the levels of rock strata and fossils to organize Earth’s history (Disciplinary Core Idea). This alignment is particularly strong on Days 3 and 5. For example, on Day 3, students use the patterns discovered through their analysis of “fossils” found in the “Earth cups” to create a relative timeline. On Day 5, students examine succession charts of three National Parks, again looking for patterns in the data. Students then use this information to make connections between the geologic histories of the parks.

  • Instructional Supports: Throughout the unit, the authors use scientifically accurate and grade appropriate vocabulary and information. In each lesson, students have multiple opportunities to discuss their ideas and receive feedback. The activities created by the authors incorporate authentic and meaningful scenarios. On Day 5, in particular, students use actual information on the rock strata found in three National Parks to make geologic comparisons. The authors have not included specific suggestions for differentiation; however, they do mention strategies, such as Team Jigsaw and Numbered Heads, to assist all students when exploring their thinking.

  • Monitoring Student Progress: The authors have provided examples of possible formative assessments in the Teacher Guide. These examples include the use of both overarching questions and diagrams to measure student progress. The authors provide multiple guiding questions for teachers to use in whole class discussions; however, the questions are not three-dimensional in nature and only assess if students are understanding content. Aligned rubrics and scoring guidelines are not provided; however, the authors do provide possible answers for the student questions included in the guide.

  • Quality of Technological Interactivity: Computer access in not needed in order for students to complete the activities.