Journey to the Center of the Earth: Earth's Structure

Initial Publication Date: July 3, 2015

Time required to complete this unit:

This page is under development and may be edited at any time. Some resources have not been cataloged, pending project approval.

3 weeks, or 12.5 hours, or 750 minutes (estimated)

Earth Science Content:

Key Terms: core, mantle, crust, asthenosphere, lithosphere, heat transfer, radiation, convection, conduction, differentiated, seismic wave, hotspots, mantle plume, sea mounts, magnetic field, magnetosphere, magnetic portal

Unit Storyline

The Earth works in mysterious ways but Geophysicists are up to the challenge. Although the deepest well ever drilled, the Kola well in Russia, only penetrated 0.2% of the Earth's depth, geophysicists have mapped interior structures and layers throughout the entire Earth using information derived from earthquakes, gravity, heat flow, electrical currents generated by lightning storms, and the Earth's magnetic field. These studies, combined with our knowledge of the materials found in igneous rocks and meteorites, are combined to tell us about the processes that take place in the deep interior of the earth. In this unit we will show you some of the ways we have unraveled some of the deepest secrets of the earth.

Developed by the DIG Texas BlueprintsnCentral Texas Development Team

Students will be able to (do)

  • Evaluate the different types of heat transfer at work within the Earth and their roles in geologic processes.
  • Explain how different geophysical methods are utilized to interpret the Earth's structure.
  • Examine the differentiated interior structure of the Earth.
  • Explain how geologic processes account for features, such as mantle plumes and hotspots, and calculate and graph the motion history of hotspots using equations relating rate, time, and distance to predict future motions and locations.
  • Describe the formation and structure of Earth's magnetic field, including its interaction with charged solar particles to form the Van Allen belts and auroras.

Students will know

  • The Earth is composed of layers that have distinct chemical, physical and thermal properties.
  • Geophysical methods are used to help define, interpret and describe the composition of the layers of the earth.
  • Heat transfer through Earth's subsystems plays a role in multiple Earth processes.
  • Earth's magnetic field is generated by the motion of the liquid outer core, heated by the solid inner core, and is in a constant state of flux.


The activities we have selected are congruent with the Next Generation Science Standards (NGSS), and are arranged to build upon one another. Therefore, to follow the storyline we recommend that teachers complete the activities in the order provided. To open an activity in a new tab or window, right click the activity link and select the preferred option.

Determining and Measuring Earth's Layered Interior

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In this activity from IRIS, students assume the roles of scientists (theoreticians and seismologists)to test the hypothesis that Earth is homogeneous throughout. Through the use of predictions and observations with models and seismic data students discover the evidence for a layered internal structure.They develop a scale model to estimate the size of Earth's core.

Instructional Strategies: Inquiry

Resource Type: Classroom learning activity

Time Required: 90 minutes

How Do We Know What's Inside Earth?

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This article by Maia ten Brink describes how seismologists are using data from EarthScope's USArray Transportable Experiment to observe what is inside the Earth beneath North America.

Instructional Strategies: Reading

Resource Type: News or popular magazine article

Time Required: 30 minutes

Annenberg Learner: Dynamic Earth

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Dynamic Earth is an interactive tutorial contains that students can use to learn about the structure of the Earth, the movements of its tectonic plates, as well as the forces that create mountains, valleys, volcanoes, and earthquakes.

Instructional Strategies: Inquiry

Resource Type: Visualization (static visualization, animation, simulation)

Time Required: 30 minutes

Layers of the Earth

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In this activity from Scripps Institution of Oceanography, students examine the composition of Earth's layers and their response to stress and answer 9 basic, intermediate, or advanced questions.

Instructional Strategies: Reading

Resource Type: Classroom learning activity

Time Required: 50 minutes

Why is the Earth Still Hot Inside?

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In this activity developed by Aaron Keller, students learn about heat transfer as a function of the size of the object. Students heat various sized marbles or spheres, record temperature change across the items, and analyze their data. They observe that the rate of heat transfer is directly proportional to the surface area but inversely proportional to volume. Students gain proficiency in using lab equipment to make repeatable measurements.

Instructional Strategies: Inquiry

Resource Type: Laboratory investigation, experiment or demonstration

Time Required: 200 minutes

Hotspot Lesson: Hotspot Theory and Plate Velocities

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This activity from the On the Cutting Edge Reviewed Teaching Collection provides students with data on the ages of Hawaiian volcanoes and seamounts and their distance from the site of active volcanism (considered the location of the hotspot). Students graph the data and estimate a line of best fit to determine the plate velocity (slope of the best fit line). This lesson defines hotspots and shows why scientists think they represent a possible mantle plume.

Instructional Strategies: Inquiry, Challenge or problem-solving

Resource Type: Classroom learning activity , Laboratory investigation, experiment or demonstration

Time Required: 90 minutes

Earth's Magnetic Field and the Sun Earth Connection

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This three-part activity explores magnetic fields and asks students to apply that newfound knowledge to explore Earth's magnetic field and how it keeps the planet habitable. This activity requires that students be familiar with the basic internal structure of Earth. They should understand that Earth has a liquid molten outer core in which circulating electric currents give rise to a magnetic field (concept of the geodynamo).

Instructional Strategies: Inquiry

Resource Type: Laboratory investigation, experiment or demonstration

Time Required: 240 minutes

ESA Euronews: Measuring Earth's Vital Magnetic Field, ESA

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Earth's magnetosphere is an invisible shield, protecting our planet from harmful solar radiation and many living organisms rely on it to navigate. Research shows the magnetic field is weakening and scientists are trying to understand why.

Instructional Strategies: Lecture

Resource Type: Video

Time Required: 12 minutes

Hidden Portals in Earth

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A NASA sponsored researcher at the University of Iowa has developed a way for spacecraft to hunt down magnetic portals in the vicinity of Earth.

Instructional Strategies: Lecture

Resource Type: Video

Time Required: 4 minutes

Field Trip

Studies that examine how geologists think and learn about the Earth point to the value of field experiences in helping students develop practices that constitute geologic reasoning. We encourage teachers to take students into the field as much as possible. To this end, we include ideas for virtual and actual field trips. The former recognizes the limitations of the K-12 classroom setting. Field learning provides a chance to encourage the ability to see features that are important to professional practice. Indeed, many geoscientists report that fieldwork was a key factor influencing their choice of geoscience as a career.

Virtual Field Trip

Layers of the Earth

The University of Kentucky has provided a tour through the layers of Earth with an explanation of P and S waves.

Scaffolding Notes

Teachers must develop their own individual plan for how they will teach the unit. The learning activities and educational resources in this unit are intended to complement other instructional activities led by the teacher. Many of the selected learning experiences provide links to excellent background preparatory materials, additional hands-on resources, teaching tips, and cross-curricular connections.

Teachers will need to create their own multimedia presentations, deliver lectures and assign ancillary work to their students in order to set the stage for effective use of the learning activities contained herein. Therefore, it is imperative to allocate time to review the activities and background material prior to using the learning experiences in this unit and to probe students for their prior knowledge before starting an activity.

In addition, although some activities may incorporate assessments, teachers may need to create their own assessments to ensure that are appropriate for the students they teach.

Asterisks (*) indicate teacher resource and background information recommendations for activity support.


*Before beginning this unit, we suggest that teachers visit the IRIS Videos website and view Elastic Rebound 1, Epicenter and Focus, and Seismic Wave Paths, and others as necessary.

In the activity Determining and Measuring Earth's Layered Interior the teacher must prepare materials in advance and make sure to read the teacher guide thoroughly, as it contains a detailed lesson plan and multiple methods for altering activities as needed. A power point is included to guide the students through the activity. The activity's modeling and graphing activities are particularly relevant to the NGSS. Teachers may consider using Excel to compile and plot all the student "seismologists" data so that there there is a more clearly defined "shadow zone" on the class graph.

*A good primer for teachers is IRIS' series of QuickTime videos at How do P & S waves give evidence for a liquid outer core?, which explain the seismic shadow zone and how it provides evidence of Earth's liquid outer core.

For the reading, How Do We Know What's Inside Earth?, teachers should be familiar with the Earth Scope program and give their students background on it and specifically the USArray project. Teachers may want to develop a set of questions to accompany the reading in order to assess students' understanding of the material and to provide for a jig-saw class discussion.

The Dynamic Earth interactive from the Annenberg Foundation opens with the question "The Earth - think it's solid as a rock?" For this unit the Earth's interior structure is to be explored by students as opposed to the entire interactive. Teachers can decide how they want to approach this with their students through possible student diagramming, whole class discussion, jigsaw, or pair-share activities. Additional chapters in this collection pertain to plate tectonics and are used in other DIG Texas units.

Layers of the Earth is an interactive diagram with questions for students to answer. It shows two views simultaneously of how geoscientists classify Earth's layers. Level-based questions are provided. Teachers may develop additional questions to ask their students or ask students to come up with questions of their own. Teachers should be sure that they understand the meaning of "stress" as it relates to geology.

Why is the Earth Still Hot Inside? is an inquiry lab with opportunities to practice lab and math skills. This is a really nice opportunity to incorporate technology in the classroom if you have access to probes and/or calorimeters. We highly recommend that teachers test this lab activity before doing it in class with students. The background information is interesting and relevant to many areas of science.

Hotspot Theory and Plate Velocities activity From SERC's On the Cutting Edge Reviewed Teaching Collection provides students with a definition of mantle plumes and the data on the ages of Hawaiian volcanoes and seamounts and their distance from the site of active volcanism (considered the location of the hotspot). The PowerPoint lecture on Mantle Plumes should be the introductory activity for this resource. After assuring the students understand the relationship between mantle plumes and hotspots, return to the Hotspot Theory and Plate Velocities main page to complete the remainder of the activity. Students then graph the data and estimate a line of best fit to determine the plate velocity of the referenced hotspots. The links for these activities are at the bottom of the webpage.

The Earth's Magnetic Field and the Sun-Earth Connection activity has 3 parts. The first is a hands-on activity that uses magnets and iron filings to create magnetic fields. In the second part the students create and use a magnetometer. In the 3rd part students explore relationships between the Earth's magnetic field and the sun. We highly recommend teachers read through the "General Information for Teachers" accessed via a link at the bottom of the page. All the necessary materials needed are listed and/or supplied through this link.

The activity includes clips from the NOVA video, Magnetic Storm. The video is available for order online, and the official website includes teacher guides and additional resources.

The European Space Agency's video, Measuring Earth's Vital Magnetic Field, provides a short introduction to the Earth's magnetic field and its "health." Posting discussion questions before showing the video is suggested.

Hidden Portals in Earth's Magnetic Field is an extension video about magnetic portals and their origins. The video can also be found at the following two links: - YouTube and - Vimeo

Next Generation Science Standards

We anticipate that students should be able to achieve the NGSS Performance Expectation(s) listed after completing the activities in this unit. However, we have not carried out educational research to verify this.

MS-ESS2-1 Describe cycling of Earth's system.

HS-ESS2-1 Develop a model to illustrate how Earth's internal and surface processes operate.

HS-ESS2-3 Develop a model based on evidence of Earth's interior to describe cycling of matter by thermal convection.

HS-ESS2-4 Use a model to describe how variations in flow of energy into and out of Earth's systems.

These Performance Expectations integrate the Disciplinary Core Ideas, Cross Cutting Concepts and Science and Engineering Practices of the NGSS as shown in the unit table NGSS Congruence: Journey to the Center of the Earth (Acrobat (PDF) 186kB Jul17 15).

Additional Resources

The recommended additional resources may be used to extend or augment the storyline.

This USGS website, Animations for Earthquake Terms and Concepts, is a glossary of earthquake terms. Included with the definition is a link to an animation of the concept.

A Virtual Journey to the Earth's Center PowerPoint presentation is a virtual journey to the Earth's center written by Purdue University for middle school/elementary. Students physically walk the distances at a scale that represent the layers of the planet. During the tour the students are presented with the key features of each layer. Additional activities and demonstrations are included at the end of the walk.

IRIS Data Products: SeisSound is an audio/video-based data product that illustrates the temporal evolution of the frequency and amplitude content of a seismogram. Conveying the seismograms frequency intent both visually and audibly produces a better understanding of the spectral content.

The Layers of the Earth takes a journey inside Earth with this video created by the Massachusetts Institute of Technology.

Live units may have permissions pending and are subject to revision.

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