Real World Ready · Layer 1: Authentic Experience

The Puzzle: What Are These Rocks Doing Here?

Every Rock Tells a Story · Part 1 of 3 · Field-Based STEM · Julian Thomson & Chris Hollis · Years 5–13

The rocks at Tora, on the east coast of the North Island, were formed from fine muds settling on the floor of a deep ocean. Over millions of years, compression and uplift turned those muds into hard, layered mudstones. But inside those mudstones, there is something that shouldn't be there: rounded pebbles. Rounded pebbles form on beaches and in rivers, not on the floor of a deep ocean. The mudstones say deep sea. The pebbles say beach. Both cannot be true at the same time. Two geologists are standing in front of this contradiction, asking a question nobody has fully answered yet. This is where your investigation begins.

Part 1 — You are here The Puzzle

Part 2 The Theory

Part 3 The Evidence

The authentic experience — before you watch

Collect rocks

Ask students to bring in rocks from wherever they find them — a garden, a beach, a riverbed, a road cutting, a driveway. Collect as many as possible.

Sort by shape

Sort the collection into two groups: rounded rocks and angular rocks. No other criteria. Just that one question: rounded or angular?

Record ideas

Ask students: what do you think caused the difference? Where might each type have come from? Record their ideas before anything else happens.

Watch the video

Listen for the moment the geologist asks the same question students just tried to answer — and notice that he doesn't have a complete answer either.

Video — Part 1: Two geologists at Tora examine rocks that sit at the K-T boundary — the moment the dinosaurs disappeared. Watch for the question, not the answer.
youtu.be/t85sNbYjaM4 · Full series: youtu.be/3RI1QtF-Tuk

AI prompts — Years 5–10

Years 5–6

Shape and placeShow AI a photograph of a rounded rock and an angular rock from your collection. Ask: "How did these rocks get their different shapes? Where might each one have come from?"

The deep sea floorAsk AI: "What does the bottom of the ocean look like 500 metres down? What kinds of rocks and creatures would you normally find there?" Compare AI's answer with the rocks in the video.

Something strangeAsk AI: "If you found a smooth beach pebble on the deep sea floor, what might have put it there?" Write down AI's ideas before watching Part 2.

Years 7–10

Rounding and transportAsk AI: "What geological processes cause rocks to become rounded? How far does a rock typically have to travel before it becomes noticeably smooth?" Test this against your own collection.

Deep sea sedimentsAsk AI: "What sediment types are normally found at 500 to 1000 metres water depth, and why? What would have to happen to deposit rounded gravel at that depth?" Record what AI says.

The K-T boundaryAsk AI: "What is the K-T boundary and why is it significant? What evidence do geologists look for to identify it?" Note where AI is confident and where it is uncertain.

AI prompts — Years 11–13

Years 11–13

Sedimentary environmentsAsk AI: "What are the characteristics of a submarine fan deposit? How would rounded, beach-derived clasts be distinguished from in-situ deep-sea sediment?" Evaluate AI's response against the video evidence.

Stratigraphic significanceAsk AI: "What is the significance of finding coarse, rounded sediment precisely at the K-T boundary? What competing hypotheses might explain this anomaly?" Identify where AI's answer is well-supported and where it speculates.

Scientific uncertaintyAsk AI to describe its confidence level in each part of its answer. Where does the evidence establish what happened, and where does the question remain genuinely open?

A guided field trip with an expert geologist is the optimal version of this experience. Where that is not possible, student-collected rocks are a genuine and often surprisingly rich starting point.

Experience Trace Scale — Part 1

Level	Years 5–6	Years 7–10	Years 11–13
1	I can sort rocks into rounded and angular and say one difference I noticed.	I can describe the anomaly Chris identifies and say why it is unusual.	I can define the anomaly in sedimentological terms and identify what makes it significant.
2	I can say where I think my rounded rocks came from and why.	I can explain what normally causes rocks to become rounded and what that tells us about their history.	I can explain the depositional environment and why rounded clasts at this depth require explanation.
3	I can say one thing AI told me and whether it matched what I saw in my rocks.	I can say where AI's answer matched the video and where it fell short.	I can critically evaluate AI's response and identify where it generalises beyond the available evidence.
4	I can say why this is a puzzle — why the rocks seem to be in the wrong place.	I can explain why the location and age of these rocks together make the anomaly significant.	I can construct the anomaly as a formal scientific question and identify what evidence would be needed to answer it.
5	I can say what question I want answered in Part 2.	I can state a hypothesis that might explain the anomaly and say what evidence would support or refute it.	I can propose a testable hypothesis and identify the stratigraphic and sedimentological evidence that Part 2 should address.

In Part 2, a theory arrives that may explain what you found. Hold your students' ideas from Step 3. They will need them.

The Puzzle: What Are These Rocks Doing Here?

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