In the style of Jules Verne’s book Journey to the Center of the Earth, take your students on a walk, using sidewalk chalk to mark the boundaries between the different layers inside our planet. After you pass through each layer, tell your students about the layer of the Earth they just traveled through. This lesson was developed by Eric Muller of the Exploratorium Teachers’ Institute. Here you will find a student handout for taking notes during the walk, a teacher cheat sheet and some assessment ideas. Download a detailed lesson plan for this activity from Eric Muller’s website, originally published in The Science Teacher, September 1995.
Can name and describe the different layers in the Earth.
Can appreciate the relative thickness of the various layers relative to familiar objects such as a human being or the tallest building.
10 min introduction
35-40 min walk
Sidewalk around 2-3 city blocks (640+ meter loop)
The earth is composed of many distinct layers. Their identity has primarily been inferred from seismic data and from analysis of the magma welling up out of volcanoes. A table of the various layers and a brief description of each follows (this same information is provided on the Earth Journey Teacher Cheat Sheet).
|Layer||Actual dist. from center||Description|
(6400-5200 km from surface)
|Metal (iron and nickel)
3-5 million atmospheres of pressure
Solid – Even though the temperatures are tremendous, the pressure is also so tremendous that the inner core is squeezed into a solid state.
(5200-2900 km from surface)
|Metal (iron and nickel)
1-2 million atmospheres of pressure
Liquid – Since there’s less pressure, the outer core can flow as a liquid and its motion is thought to generate Earth’s magnetic field.
(2900-100 km from surface)
1 million atmospheres of pressure
Near-solid to liquid – Near the core, the mantle is a plastic solid, meaning that it is a liquid but it incredibly viscous and flows incredibly slowly. It becomes more liquid and less viscous as you move outward and the pressure decreases.
|Lithosphere and crust||
(100-0 km from surface)
|Rock and ocean
Very low temperature and pressure
Solid (except for the ocean)
The lithosphere forms the tectonic plates. The bottom of the lithosphere is technically still part of the mantle. Riding on top of the lithosphere is the crust, the layer we live on (between 5-70 km deep).
I structured the walk for 640 m since the calculations become very easy from the actual distances to the walk distance (and thus is easy for kids to see the relationship). In addition, if the 640 m walk is arranged in a loop, it is quite easy to fit the walk into a regular 45-50 minute period.
Download a detailed lesson plan for this activity from Eric Muller’s website.
Have students complete the handout during the walk or afterwards. As you describe each part of the journey, students can label the borders between each layer and describe the composition, temperature, pressure, and physical properties of each layer on the handout.
Plate Tectonics and Earth's Structure
1. Plate tectonics accounts for important features of Earth's surface and major geologic events. As a basis for understanding this concept:
b. Students know Earth is composed of several layers: a cold, brittle lithosphere; a hot, convecting mantle; and a dense, metallic core.
c. Students know lithospheric plates the size of continents and oceans move at rates of centimeters per year in response to movements in the mantle.