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Karst

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Why this lesson, and why the 3D

Karst 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: Limestone does not just break. It dissolves along joints: pavement, swallow hole, cave. By the end of the slot a pupil should be able to read clints and grykes, a sinkhole, and a cave passage. Curriculum tags in the header (GCSE; A-level carbonation) are filters, not a flag. The room is worldwide; SI first; International English. Ages on the card (KS3, GCSE, A-level) are a suggested band, not a gate.

Limestone does not just break. It dissolves along joints: pavement, swallow hole, cave. The Yorkshire Dales are the UK classroom — Malham Cove’s clints and grykes, Gaping Gill taking Fell Beck underground, a resurgence kilometres away. Mammoth Cave, Kentucky, is the US pair: a long, lower-gradient carbonate system in Mississippian limestone, sinkholes on the Chester Upland, the same chemistry at a different map scale. GCSE and A-level carbonation both need that sequence. Soil is thin. Farmers talk limestone in the same breath as drainage. Students who think caves are lava tubes, or that every hole is a volcano, will misread both Malham and Mammoth. Granite does not do this. Chemistry, not magnetism. A surface watershed on limestone may not match the cave.

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

Pavement first. Clints are the blocks. Grykes are the dissolved fissures between them. A stream swallows. That is the swallow hole, where drainage leaves the surface. Toggle Cave cutaway on. A passage in carbonate, not a lava tube. These are solution caves. Carbonation of calcium carbonate along joints. Granite does not do this. Every hole is not a volcano. That is the misconception, plus the lava-tube mix-up. Karst clusters on carbonate rocks because of chemistry, not magnetism. Yorkshire Dales pavement and Mammoth Cave are the pair. Gaping Gill is the UK poster for a swallow. Vertical exaggeration is ×6 and labelled. Finish in Check.

Open the lab full screen (F). Labels on (L). Speak the first step before you touch a slider: Pavement: clints and grykes. Then the second: A stream swallows. Toggle the cutaway cave. Then the third: Carbonation plus joints. Granite does not do this.

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

Pavement first. Clints are the blocks. Grykes are the dissolved fissures between them. A stream swallows — that is the swallow hole, where drainage leaves the surface. Toggle Cave cutaway on. A passage in carbonate, not a lava tube. Keyboard: L labels, R reset. Vertical exaggeration is ×6 and labelled. Granite does not do this. Say so. Finish in Check. Yorkshire Dales pavement and Mammoth Cave are the pair. Every hole is not a volcano. Gaping Gill is the UK poster for a swallow.

The in-site film is “What is Weathering? Crash Course Geography #21” (Crash Course Geography, about 11 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.

“Caves are lava tubes.” — no. These are solution caves in carbonate. Carbonation along joints.

“Every hole is a volcano.” — no. A swallow hole is where a stream leaves the surface on limestone. Not magma.

“Granite does this too if it rains hard enough.” — no. Karst clusters on carbonate rocks because of chemistry, not rainfall volume alone.

Pitfalls to keep in your pocket: Every hole is a volcano. Calling solution caves lava tubes. Teaching granite as a karst rock. 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

Rainwater picks up carbon dioxide and becomes a weak carbonic acid. It works on calcium carbonate along bedding and joints. The surface becomes a limestone pavement: clints are the blocks, grykes the dissolved fissures. A stream that meets a swallow hole (sinkhole, doline) leaves the surface and may return as a resurgence. Cave passages follow joints and bedding; stalactites need a drip with time. Carbonation plus joints is the machine. Granite does not dissolve that way; these are solution caves in carbonate, not lava tubes. Toggle the cutaway and the chamber appears under the doline. Vertical exaggeration is labelled ×6 so pavement, grykes, and the doline cone read from the back of the room. True grykes on a table would be scratches. The pavement is a schematic block, not a traced Malham sheet. Gaping Gill is the UK poster for a swallow. Mammoth Cave is the long US system. Karst clusters on carbonate rocks because of chemistry. Sequence it: rainfall, carbonation, widened joints, swallow hole, cave passage, then a stalactite if the drip has time. Gordale Scar is a different argument — a gorge, possibly collapse or meltwater — still useful, still not a volcano.

The first place to land is Yorkshire Dales. The second is Mammoth Cave. 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: Tower karst or a cave in carbonate rock. Carbonation along joints. Credit: Wikimedia Commons, CC BY-SA.

Mechanism photograph: Field or official figure for teaching Karst. 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.

Limestone pavement: Clints and grykes on a bare carbonate surface. Clint: The block on a limestone pavement. Gryke: Dissolved fissure between clints. Exam language also accepts “Grike”. Swallow hole: Point where drainage leaves the surface. Exam language also accepts “Sinkhole / doline”. Carbonation: Weak carbonic acid working on calcium carbonate. Resurgence: Where underground drainage returns to the surface. Stalactite: Dripstone growing down from a cave roof, if the drip has time.

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: carbonation of limestone along joints makes pavement, swallow holes, and solution caves. Clints and grykes. A swallow is where a stream leaves the surface. These are not lava tubes. Granite does not do this. Yorkshire Dales and Mammoth Cave are the pair. Vertical exaggeration is ×6 and labelled. Chemistry, not magnetism. Gaping Gill is the UK poster. A surface divide on karst may not match the cave beneath. Sequence rainfall to stalactite if you have time.

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. BGS karst; NPS Mammoth Cave.

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; A-level carbonation) are filters, not a flag. A class in Nairobi, London, or Shanghai can use the same 3D. Ages (KS3, GCSE, A-level) 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: Limestone does not just break. It dissolves along joints: pavement, swallow hole, cave. Two: the misconception “Caves are lava tubes.”. 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 cutaway. Send them home with the same link; there is no login.

In-site film

What is Weathering? Crash Course Geography #21. Crash Course Geography. Crash Course / Complexly on YouTube. Standard YouTube licence. Educational embed, autoplay off. Autoplay off.