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Soil erosion

All teacher notes · Open the lab · 1983 words · ·

Why this lesson, and why the 3D

Soil erosion 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: Rain splash, rill, wind. Vegetation on, the A horizon stays. Vegetation off, it leaves. By the end of the slot a pupil should be able to toggle cover and watch splash, rill, and wind. Curriculum tags in the header (GCSE; APES 4.3; NGSS) are filters, not a flag. The room is worldwide; SI first; International English. Ages on the card (KS3, GCSE, NGSS MS, APES) are a suggested band, not a gate.

An A horizon is a budget, not an infinite floor. Cover and roots hold it. Bare ground gives it away. The Dust Bowl on the southern Great Plains is the US scale of that sentence: prairie plough, drought, wind, and silt that left the county. UK pairs are smaller and wetter — peaty upland scars, Somerset Levels fields that lose fines when winter rain sits on bare maize, Jurassic Coast and Dales slopes that rill after a wet week. Same physics, different storm. GCSE and APES both want splash, rill and wind named before anyone reaches for a sermon. Raindrop impact detaches. Flow concentrates into rills, then gullies. Wind lifts dry loose grains: deflation. Vegetation raises roughness, intercepts drops, and ties particles with roots. Grand Canyon walls are rock weathering plus export; this lab is the soil skin. Process first. History second. The 1930s are this toggle in the archive, not a morality play without a mechanism.

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

Two plots. Bare on the left, cover on the right. Play the storm. Splash detaches, then rills cut, then wind on the bare plot. Rain splash is the first move. A rill is a small channel. Then gully. The vegetated plot holds. Cover and roots slow water and wind. Soil is not infinite. An A horizon is a budget. Dust Bowl spent it. That is the misconception. Dust Bowl is this toggle in history. Peaty UK uplands and Somerset bare fields are the same idea at smaller scale. Process first, then the history. Do not moralise without the mechanism. Name splash, rill, deflation before you sit down. Finish in Check.

Open the lab full screen (F). Labels on (L). Speak the first step before you touch a slider: Bare soil. Splash. Rill. Wind. Then the second: Vegetation on. Then the third: Dust Bowl is this toggle in history.

The sliders that earn their keep are Vegetation. Space plays; arrows nudge time; R resets. Parameters the URL can remember: veg. 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.

Two plots sit side by side. Left is bare: play the storm and watch splash drops, then rills cut the surface, then a wind arrow. Right is cover: cones of vegetation, the A horizon intact. Play through a storm cycle. Orbit from the bare rills to the vegetated plot. Read the studio line: storm fraction, bare rills, vegetated plot stays. Name splash, rill, deflation out loud before you sit down. If Vegetation is on the bar, leave the comparison as two plots; the mechanism is cover versus none. Dust Bowl is the history after the process.

The in-site film is “What is Soil (and Why is it Important)? Crash Course Geography #16” (Crash Course Geography, about 10 min, Crash Course / Complexly on YouTube. Standard YouTube licence. 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.

“Soil is infinite.” — no. A horizon is a budget. Dust Bowl spent it.

“Only wind erodes soil.” — no. Splash and rill are water. Wind is the dry extra. Name all three.

“Vegetation is decoration.” — no. Cover and roots are the hold. Bare is the experiment.

Pitfalls to keep in your pocket: Moralising without process. Wind-only story on a wet UK field. Calling every channel a canyon. Inventing Dust Bowl tonnages. 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

Detachment, then transport, then deposition somewhere else. Rain splash is the first detachment on bare soil: a drop hits, a particle jumps, a crust can form. Once water flows, shear in tiny threads cuts rills — small channels you can step across — which can deepen into gullies. Gradient, texture and storm intensity set the rate. Clay and silt travel in suspension; sand hops. Wind needs dry, loose, unsheltered grains; it is deflation and saltation, the Dust Bowl headline, not a desert-dune textbook by default. Vegetation works three ways: canopy intercepts splash, stems slow water and wind, roots bind. Take the cover off and the same storm writes channels on the plot. Keep it on and the A horizon stays. The lab exaggerates rill depth so the class can see them; real rills are often centimetres. That caption is on the studio. Texture from the triangle lab matters here: silt is easy to lift; a Somerset clay may slake and crust; a sandy A can both drain and blow. Land use is a roughness choice. The physics does not moralise. It just moves particles when nothing holds them.

The first place to land is Dust Bowl. The second is Loess Plateau. 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: A gully cut into a soil slope. The A horizon can leave. Credit: USDA / public domain.

Mechanism photograph: Field or official figure for teaching Soil erosion. A second photograph for the projector script — not the lab cover. Credit: Wikimedia Commons / NASA / USGS.

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.

Rain splash: Drop impact that detaches particles at the soil surface. Rill: Small erosional channel cut by running water. Can grow into a gully. Gully: Larger than a rill; a channel you cannot remove with ordinary tillage. Deflation: Wind removing loose particles from a surface. A horizon: Upper mixed mineral-organic soil. The budget this lab spends. Cover: Vegetation or residue that intercepts splash and raises roughness. Saltation: Grains hopping in wind or water. Sand’s usual travel mode.

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 canvas the toggle is still the lesson. Bare soil: rain splash detaches, rills cut, wind can lift dry fines. Vegetation on: cover and roots hold the A horizon and slow water and wind. A rill is a small erosional channel; a gully is the next size. Deflation is wind removing loose particles. Soil is not infinite. Dust Bowl spent a prairie A horizon. Somerset Levels and UK uplands are the same idea at smaller, wetter scale. Process first. Then the history. Name splash, rill, wind. Then sit down.

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. USDA NRCS; NOAA Dust Bowl.

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 (GCSE; APES 4.3; NGSS) are filters, not a flag. A class in Nairobi, London, or Shanghai can use the same 3D. Ages (KS3, GCSE, NGSS MS, APES) 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: Rain splash, rill, wind. Vegetation on, the A horizon stays. Vegetation off, it leaves. Two: the misconception “Soil is infinite.”. 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 veg. Send them home with the same link; there is no login.

In-site film

What is Soil (and Why is it Important)? Crash Course Geography #16. Crash Course Geography. Crash Course / Complexly on YouTube. Standard YouTube licence. Educational embed, autoplay off. Autoplay off.