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KS3 Earth and atmosphere · 15 minutes · no login

Earth’s interior

All teacher notes · Open the lab · 2094 words · ·

PREM-style labelled cutaway of crust, mantle, outer core and inner core. — A second crop of the labelled interior figure for the projector script — not the lab cover. Crust is a film; mantle is solid rock. Source: Wikimedia Commons Earth internal structure, CC teaching figure.Wikimedia Commons / USGS-style cutaway, CC

Why this lesson, and why the 3D

Earth’s interior is a fifteen-minute projector lesson, not a homework packet and not a film with a quiz bolted on. Put this hook on the board before you dim the lights: A cut apple is a bad model of Earth: the ‘skin’ would be thinner than the apple’s, and the outer core is liquid metal. By the end of the slot a pupil should be able to name the four main layers, their state, and why a liquid outer core plus P/S-wave shadows tell us the inside is not uniform rock. Curriculum tags in the header (KS3 Earth and atmosphere; GCSE AQA 3.1.1; NGSS MS-ESS2-1; A-level plate tectonics background) are filters, not a flag. The room is worldwide; SI first; International English. Ages on the card (KS3, GCSE, A-level, NGSS MS, HS Earth Sci) are a suggested band, not a gate.

The Kola Superdeep borehole, on the Kola Peninsula, reached a little over 12 km — a scratch on a 6371 km radius. Yellowstone’s magma is still in the crust. A cut apple is a bad model: the skin would be thinner than the apple’s, and the outer core is liquid metal, not fruit. UK GCSE AQA 3.1.1 and NGSS MS-ESS2-1 both need the four layers by name and state. If the mantle looks like lava, students keep the magma-ocean myth the copy is trying to kill. Holderness till and Himalayan rock both sit on that thin crust. San Andreas is a crustal slide, not a window into the core.

The 3D is a named, inspectable object. Click the part, not a caption. If the model will not spin, the Why panel still carries the mechanism, the two photographs, and the film. Do not apologise for the model. Drive it. A silent spin teaches a screensaver. A named mesh that changes under a slider teaches the process.

Fifteen minutes on the projector

Explode the shells. Ask which layer is liquid before you reveal the key. Slice. The crust is a film. Say that out loud. The mantle is solid rock that creeps. It is not a magma ocean. Fire S-waves. Wait until the class sees them die at the outer core. Then P-waves and the shadow zone. Close on the magnetic field as a liquid-core story, not a bar magnet in a kit. Caption stays: crust drawn ×4. Mantle is solid rock. E explode. X slice. Space play. P projector. Finish in Check.

Open the lab full screen (F). Labels on (L). Speak the first step before you touch a slider: Spin the intact Earth, then explode the layers. Crust, mantle, outer core, inner core. Read thicknesses and state. Then the second: Slice. Fire a P-wave and an S-wave from a surface quake. S-waves stop at the liquid outer core. P-waves leave a shadow zone. Then the third: We have never drilled the mantle. Layering is inferred from seismic waves, density, and the magnetic field that needs a convecting liquid metal outer core.

The sliders that earn their keep are P/S waves. E explodes the cut so inner surfaces can be named from the back of the room. X slices the volume so a hidden plane can be seen. Space plays; arrows nudge time; R resets. Parameters the URL can remember: waves. If you only have eight minutes, skip the last step and finish in Check. Projector layout (P) is for the back row: one idea, large type, the model still live.

Explode pulls the shells apart. Slice cuts a plane. Toggle P/S waves or press play. Keyboard: E explode, X slice, L labels, R reset, Space play, P projector. Ask which layer is liquid before you reveal the key. Fire S-waves and wait until they die at the outer core. Then P-waves and the shadow zone. Close on the magnetic field as a liquid-core story, not a bar magnet in a kit. The caption stays on: crust ×4, mantle is solid rock.

The in-site film is “Compositional and mechanical layers of the Earth” (Khan Academy, about 12 min, Khan Academy on YouTube. CC BY-NC-SA. Educational embed, autoplay off.). Autoplay is off. Play one minute if you need a second voice; do not let the film eat the slot. The 3D still has to move under your hand.

What the third row will get wrong

You will hear the misconception before you have finished the first sentence. Write the false claim on the board and leave it there until the model has contradicted it. Do not skip this. A fluent pupil can recite the hook and still believe the false sentence.

“The mantle is a sea of molten lava.” — no. The mantle is overwhelmingly solid. Magma is a local, partial melt. The liquid layer is the outer core, and it is metal, not lava.

“We have samples from the core, like we have Moon rocks.” — no. We have not. The deepest borehole is crust. Core composition is inferred from seismology, density, and meteorite chemistry.

“The crust is a thick layer you could walk around inside.” — no. Continental crust averages about 35 km on a 6371 km radius. This lab draws it ×4 so you can see it. It is a film.

Pitfalls to keep in your pocket: Textbook colours that look like lava for the whole mantle. Saying we have ‘samples from the core’ — we have not. Calling the crust thick because this lab draws it ×4. The caption is the truth. Do not let a pupil leave thinking the 3D is a photograph. It is a teaching model. Where vertical exaggeration exists, T collapses it and the caption says so. A labelled lie of scale is honest. An unlabelled one is a cartoon.

Two places, not a slogan

Four layers, four jobs. Crust: a thin rigid skin — oceanic about 7 km, continental about 35 km, drawn ×4 here so you can see it. Mantle: solid silicate rock that creeps over geologic time. It is not a magma ocean. Partial melt exists in thin zones; the bulk is solid. Outer core: liquid iron–nickel. S-waves die there. That liquid metal, stirring, is the school story of the magnetic field. Inner core: solid iron–nickel, crystallising as the planet cools. What moves in this lab: explode offset, slice plane, P- and S-wave fronts. What does not: the order of the four, the fact of a liquid outer core. What is conserved: seismic rules — P through liquid, S not. The lie the model tells is crust thickness. Mantle colour is rock, not lava. Outer core is metal in slow spin, not fire.

The first place to land is Kola Superdeep borehole. The second is Yellowstone — a mantle plume. Same process, different rock or climate. If a pupil can only name one place, they have a postcard, not a mechanism. Atlas entries for those names are a click from the case list; send them back to the lab with one sentence they can say in Check.

Do not flatten the comparison into “this country versus that country.” Name the landform. Holderness is till, not chalk. Hawaii is a hotspot, not an island arc. Yosemite is a glacial trough, not a river canyon. The 3D is allowed to be schematic; the place names are not allowed to be sloppy.

Figures and the film

Field photograph: PREM-style labelled cutaway of crust, mantle, outer core and inner core. Four layers, four states. Crust is a film; mantle is solid rock; the outer core is liquid metal. Source: Wikimedia Commons Earth internal structure, CC teaching figure. Credit: Wikimedia Commons / USGS-style cutaway, CC.

Mechanism photograph: PREM-style labelled cutaway of crust, mantle, outer core and inner core. A second crop of the labelled interior figure for the projector script — not the lab cover. Crust is a film; mantle is solid rock. Source: Wikimedia Commons Earth internal structure, CC teaching figure. Credit: Wikimedia Commons / USGS-style cutaway, CC.

Two photographs, two jobs. The field picture is the place. The mechanism picture is the process. Do not run the lesson on a single Apollo Earth disc. A carbon-cycle class is a forest and a seam, not a blue marble. An ENSO class is a Pacific temperature map, not Africa from Apollo 17.

Words they must be able to say

Say these out loud once while you click the matching mesh. If a word has no mesh, it still has a photograph in Terms.

Crust: Rigid outer rock. Oceanic ~7 km; continental ~35 km. Mantle: Solid but convecting silicate rock to ~2900 km. Most of Earth’s volume. Not a magma ocean. Outer core: Liquid iron–nickel. S-waves stop here. Source of the magnetic field. Inner core: Solid iron–nickel sphere ~1220 km in radius. P-wave: Travels through solid and liquid. Fastest. Exam language also accepts “Primary / compressional wave”. S-wave: Travels through solids only. Dies in the outer core. Exam language also accepts “Secondary / shear wave”. Lithosphere: Crust plus the rigid top of the mantle. Plates are lithosphere, not crust alone. Geodynamo: Magnetic field generated by convection in the liquid, conducting outer core.

Exam-language toggle (the Teacher tab) swaps UK/US pairs where they exist — levée/levee, arête/arete — so a mixed room is not punished for spelling.

Close the slot

Without the 3D view: Earth is a thin rocky skin, a solid convecting mantle, a liquid metal outer core, and a solid metal inner core. Crust is kilometres, not hundreds. Mantle is not lava. S-waves stop at the outer core; P-waves go through. Kola was a scratch. Yellowstone is crustal. The apple is a bad model. That paragraph is the lab if WebGL is off, and it is the sentence that kills ‘magma ocean’.

Finish in Check — ten questions, not a mood. The bank mixes definition, process, the misconception you just killed, a named place, and a read-the-model item (click the part; T). If a pupil can only recite the hook, they have not used the geometry. Wrong answers still show the one-line explain. Do not skip the explain.

Sources on the Teacher tab are the trail, not a bibliography to copy. USGS — Earth’s interior; BGS — seismology; PREM density model (Dziewonski & Anderson).

Link back to the live lab and keep the same slug. Do not invent a parallel worksheet that contradicts T, SI, or the named parts.

This note is worldwide. Curriculum tags (KS3 Earth and atmosphere; GCSE AQA 3.1.1; NGSS MS-ESS2-1; A-level plate tectonics background) are filters, not a flag. A class in Nairobi, London, or Shanghai can use the same 3D. Ages (KS3, GCSE, A-level, NGSS MS, HS Earth Sci) are a suggested band. If a sentence only works in one exam board, rewrite it before you project it.

Write these three lines on the board before you dim the lights. One: A cut apple is a bad model of Earth: the ‘skin’ would be thinner than the apple’s, and the outer core is liquid metal. Two: the misconception “The mantle is a sea of molten lava.”. Three: the named parts they must click. Then drive the model. Check is ten questions covering definition, process, the misconception, a place, and a read-the-model item. Do not skip the explain on a wrong answer.

Board, units, and what not to say

SI first. Metres, kilometres, degrees Celsius, metres per second. A conversion in brackets is courtesy, not a second system. Do not let a pupil leave thinking the 3D is a photograph. It is a teaching model. Where vertical exaggeration exists, T collapses it and the caption says so.

Do not say “teaching mesh”, “sprinkle”, or “thin free surface not a fat pipe” out loud. Say the landform. Seasons are ~23.44° of axial tilt, not Earth–Sun distance. The outer core is liquid; S-waves do not pass. Yosemite is a glacial U-trough. San Andreas is a transform. Hawaiʻi and Yellowstone are hotspots. Florida is not a glacial trough.

If the room is noisy, projector layout (P) is the back-row setting: one idea, large type, the model still live. Full screen (F). Labels (L). Space plays. Arrows nudge time. R resets. The URL can remember waves. Send them home with the same link; there is no login.

In-site film

Compositional and mechanical layers of the Earth. Khan Academy. Khan Academy on YouTube. CC BY-NC-SA. Educational embed, autoplay off. Autoplay off.