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Tides

All teacher notes · Open the lab · 2058 words · ·

Why this lesson, and why the 3D

Tides 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: Two bulges. Spring and neap are alignment, not emotion. By the end of the slot a pupil should be able to show two tidal bulges and spring/neap with Moon–Sun alignment. Curriculum tags in the header (KS3; GCSE coasts; NGSS MS-ESS1-1) are filters, not a flag. The room is worldwide; SI first; International English. Ages on the card (KS3, GCSE, NGSS MS) are a suggested band, not a gate.

Holderness waves ride a tidal range. Estuaries even more. The Mississippi meets a modest Gulf tide and still dumps a delta; UK east-coast mudflats live on a larger clock. Spring and neap are alignment, not April. A Leeds student who thinks spring tide waits for daffodils will misread every tide table from the Humber to Miami. Yosemite has no sea, but the same Moon that pulls Holderness pulls a California coast twice a day. Hawaii sits in a different basin with a different range; the two-bulge idea still holds as the school start. Fieldwork on a UK beach is a timetable. Miss the range and you miss the spit, the mud, the harbour gate. The skill is two bulges, then syzygy versus quadrature. Wind is weather. Rivers are catchments. Neither is the second bulge.

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

Play the month. Two bulges: one toward the Moon, one opposite. That two-bulge picture is a school model. Flag the simplification. When Sun and Moon pull along one line, the range is larger: spring tide. Spring as in leap, twice a month, not the season. At right angles the bulges fight: neap tide, smaller range. The Sun is weaker than the Moon here, but not zero. Ask which phase gives spring: new or full — both, syzygy. Quarter moons give neap. Spring tides do not wait for April. That is the trap. Finish in Check.

Open the lab full screen (F). Labels on (L). Speak the first step before you touch a slider: Two bulges: toward the Moon and opposite. Then the second: Play the month. Align Sun and Moon: spring. Right angle: neap. Then the third: Sun is weaker but not zero.

Time, labels, and T (true scale) are the whole desk. Play walks the process; T removes the vertical lie where one was drawn. Space plays; arrows nudge time; R resets. Parameters the URL can remember: t, labels, true scale. 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.

Play the month. Space toggles play. Arrows nudge time. Speed 1×, 2×, 4×. No extra slider. No toggle. L labels. R reset. P projector. No explode, no slice. Pause when the readout says spring — Sun and Moon aligned. Pause on neap — quadrature. Ask which phases give spring before you reveal: new or full, both. Quarter moons give neap. Reset if the class has named the season by accident. The month slider is the only clock. Watch the mesh deform; it is not a sticker. Name spring and neap from alignment, not from the calendar.

The in-site film is “How Do Oceans Circulate? Crash Course Geography #9” (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.

“Spring tides happen in April.” — no. Spring as in leap, twice a month.

“There is only one bulge, the one facing the Moon.” — no. Two. Toward the Moon and opposite. The second is the school-model surprise.

“The Sun does not affect tides.” — no. Weaker than the Moon, not zero. Alignment is why springs beat neaps.

Pitfalls to keep in your pocket: Season named spring. Only one bulge, facing the Moon. Calling a tsunami a tide, or wind setup the two-bulge clock. 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

Input is a month. The Moon goes around. The Sun sits off-stage, weaker, not zero. Two bulges: one toward the Moon, one opposite. That opposite bulge is the school model — gravity plus the orbiting-system’s inertia — and the teacher notes flag the simplification. What moves: the Moon’s place, which way the fat water points, whether the Sun’s smaller pull adds or fights. What does not: the existence of two bulges, Earth’s spin as the thing that carries a coast through those bulges twice a day, in the simple picture. What is conserved: mass of water, the fortnightly spring–neap beat, the fact that new and full are both syzygy. Align Sun and Moon along one line: spring tide, larger range, twice a month, named for leaping, not the season. Right angles: neap, smaller range, quarter moons. The lie the model tells: water is a deformed mesh around a smooth globe; continents do not get in the way; real amphidromes, basins, and coastal funnelling are missing. Holderness and the Gulf are not the same range. The mechanism still starts here. Tsunamis are not tides. Wind setup is not the two-bulge clock.

The first place to land is Holderness coast. The second is Modest Gulf tides. 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 tidal flat at low water — the sea left. A tidal flat at low water — the sea left. This is the classroom sense of tides: a named landform, process, or object. Source: Wikimedia Commons / NASA / USGS / NOAA, public domain or CC. Credit: Wikimedia Commons / NASA / USGS / NOAA, public domain or CC.

Mechanism photograph: Field photograph or official scientific figure for teaching tides. Field photograph or official scientific figure for teaching tides. A second photograph for the projector script — not the lab cover. Source: Wikimedia Commons / NASA / USGS / NOAA, public domain or CC. Credit: Wikimedia Commons / NASA / USGS / NOAA, public domain or 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.

Spring tide: Larger range. Sun and Moon pull along one line. New or full. Twice a month, not the season. Exam language also accepts “Syzygy tide”. Neap tide: Smaller range. Sun and Moon at right angles. Quarter moons. Exam language also accepts “Quadrature tide”. Syzygy: Sun, Moon, and Earth in one line. Spring tide. Exam word for the alignment. Quadrature: Sun and Moon at right angles as seen from Earth. Neap tide. Tidal bulge: A school picture: one bulge toward the Moon, one opposite. A simplification, flagged as such. Tidal range: High water minus low water. Springs large, neaps small. Coasts then reshape the number. Semi-diurnal tide: Two highs and two lows in about a day, in the simple spinning-through-bulges picture.

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

If the bulges will not spin, keep the sentences. Two bulges: toward the Moon and opposite. Spring tide is larger range when Sun and Moon pull along one line, twice a month, not in April. Neap is smaller range at right angles. The Sun is weaker than the Moon here, but not zero. Holderness rides a real range. Gulf tides can be modest. This is a school two-bulge model, not a harbour forecast. That is enough for Check on paper.

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. NOAA tides; UKHO.

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; GCSE coasts; NGSS MS-ESS1-1) are filters, not a flag. A class in Nairobi, London, or Shanghai can use the same 3D. Ages (KS3, GCSE, NGSS MS) 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: Two bulges. Spring and neap are alignment, not emotion. Two: the misconception “Spring tides happen in April.”. 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 t, labels, true scale. Send them home with the same link; there is no login.

In-site film

How Do Oceans Circulate? Crash Course Geography #9. Crash Course Geography. Crash Course / Complexly on YouTube. Standard YouTube licence. Educational embed, autoplay off. Autoplay off.