Fossils: how a living thing turns to stone and how we dig it up

Tests: 4 of 11 right · Exam: 1 of 4 right · Kind: plain · Understood: 10 of 15 · Run: 2026-10-18, commit f3c23ea72

Lesson 275 of the biology course of Mova's primary school, as Mova's small model took its tests: it had read this lesson and the ones before it and learned from their exercises. Each test shows the options in the order the student saw them, its choice, the right answer, the score of every option and why it chose. The lesson itself, sentence by sentence with trees and pragmatics: the lesson in the corpora.

Every question of this lesson and each of its options parsed by Mova, with trees and pragmatics: the lesson's questions in the corpora.

Test 1 · wrong ✗

«found a curly stone on the beach, my nan says it's a snake turned into stone» What is right?

1. Yes, snakes curl up tight and then turn to stone when they die — score 7
2. It is a stone polished by waves, never alive — ← Mova's choice · score 8
3. It is a snail that died last summer — score 5
4. It is most likely an ammonite, a sea animal with a coiled shell — ✓ the right answer · no support

Why: It took the question to ask which statement is true. It chose option 2 with score 8, against 7 for the next best. Its support: lesson 275, line 4: «That is why the curly stone you pick up on a beach is so special: it is the shape of a sea animal that died long before the first person walked the Earth.», reached through the option's own match among the sentences about the question's things. What matched: the same doer «stone» (+3); the same light verb (be, have, do, get, go) (+3); the same thing acted on «shape» (+2). The right option, 4, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 2 · right ✓

«mate reckons every dinosaur that ever lived turned into a fossil, that's why museums have so many» What is right?

1. No, far fewer than one in a million animals becomes a fossil — ← Mova's choice · ✓ the right answer · score 7
2. No, none of them did, fossils are all plaster — no support
3. Yes, every bone turns to stone in the end if you wait long enough — score 4
4. Yes, but only the big ones — no support

Why: It took the question to ask why something happens (its cause). It chose option 1 with score 7, against 4 for the next best. Its support: lesson 275, line 10: «Far fewer than one in a million animals becomes a fossil, because most bodies are eaten, rot or are broken up; only a quick burial without air gives a chance.», reached through the option's own match among the sentences about the question's things. What matched: the same action «become» (+4); the same thing acted on «fossil» (+3). · the question and its options parsed, with trees and pragmatics

Test 3 · wrong ✗

What would happen to a dead fish lying on the seabed for years without being buried?

1. It would turn to stone in a few weeks, as all dead fish do in the sea — ← Mova's choice · score 6
2. It would most likely be eaten or rot away and leave no fossil — ✓ the right answer · score 5
3. It would float up and become a cloud — score 5
4. It would grow into a new fish — score 6

Why: It took the question to ask which statement is true. It chose option 1 with score 6, tied with another option at 6 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 203, line 10: «Fish that are small enough to fit in another fish's mouth may be eaten, so owners check how big each fish will grow before putting them together.», reached through the option's own match among the sentences about the question's things. What matched: the same action «grow» (+3); the same doer «fish» (+3). The right option, 2, scored 5. · the question and its options parsed, with trees and pragmatics

Test 4 · wrong ✗

Count them: a museum shows 3 fossil footprints of a two-legged dinosaur, each with 3 toes. How many toe marks are there in all?

1. 6 — ← Mova's choice · no support
2. 9 — ✓ the right answer · no support
3. 12 — no support
4. 3 — no support

Why: No option found support in what it remembers, so it guessed: it took the first option shown. · the question and its options parsed, with trees and pragmatics

Test 5 · right ✓

«found a massive bone sticking out of the cliff, gonna dig it out with dad's hammer» What is best?

1. Leave it, keep away from the cliff and tell a museum — ← Mova's choice · ✓ the right answer · score 5
2. Dig fast before the tide comes in and washes it away — no support
3. Hit it hard so it breaks out in one go — no support
4. Take only the end that sticks out — no support

Why: It took the question to ask which statement is true. It chose option 1 with score 5, the only option with support. Its support: lesson 30, line 13: «Snakes push their bodies against bumps on the ground to move, and pythons still have tiny leg bones left from ancestors with legs.», reached through the option's own match among the sentences about the question's things. What matched: the same action «leave» (+3); the same thing acted on «tiny leg bones» (+2). · the question and its options parsed, with trees and pragmatics

Test 6 · wrong ✗

In a cartoon, a dog digs in the garden and finds a whole shiny dinosaur skeleton in one afternoon. What is closer to the truth?

1. Any dog can smell fossil bones under rock — ← Mova's choice · score 5
2. Real dinosaurs are buried in gardens just under the grass — no support
3. Real fossil bones are always white and shiny — no support
4. Real fossils are usually broken and stuck in rock, and digging one out takes months or years — ✓ the right answer · no support

Why: It took the question to ask which statement is true. It chose option 1 with score 5, the only option with support. Its support: lesson 196, line 8: «Rescue dogs can smell a person buried under snow or rubble and can search an area much faster than a line of people.», reached through the option's own match among the sentences about the question's things. What matched: the same action «smell» (+3); the same doer «rescue dogs» (+3). Against it: a different thing acted on (counts against) (-1). The right option, 4, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 7 · right ✓

«poo can't be a fossil lol» What is right?

1. It can: fossil poo is a trace fossil and shows what animals ate — ← Mova's choice · ✓ the right answer · no support
2. Only bird poo can be a fossil — no support
3. Fossil poo is just a joke in films — no support
4. Right, only hard bones and shells can ever be fossils, never poo — no support

Why: No option found support in what it remembers, so it guessed: it took the first option shown. · the question and its options parsed, with trees and pragmatics

Test 8 · wrong ✗

A man in the 1800s cuts a log of petrified wood and sees rings. What do the rings tell him?

1. The rings were made by waves on a beach — score 7
2. The tree turned to stone in one year — ← Mova's choice · score 9
3. The stone was carved by people to look like wood — no support
4. The stone was once a real tree that grew year by year — ✓ the right answer · score 6

Why: It took the question to ask what it is done to. It chose option 2 with score 9, against 7 for the next best. Its support: lesson 275, line 17: «Petrified wood is wood turned to stone as minerals replaced it cell by cell; the Petrified Forest in Arizona is full of it, and tree rings can still be seen.», reached through the same lesson line as the sentence the question matched. What matched: the same action «turn» (+6); the same place «stone» (+3). The right option, 4, scored 6. · the question and its options parsed, with trees and pragmatics

Test 9 · right ✓

«cyclops were real, they found the skulls» What is closest to the truth?

1. Mammoths really had only one eye — no support
2. Some historians think mammoth skulls with one big nose hole inspired stories of one-eyed giants — ← Mova's choice · ✓ the right answer · score 3
3. Yes, scientists have dug up real cyclops skeletons — no support
4. The skulls were of giant owls — no support

Why: It took the question to ask which statement is true. It chose option 2 with score 3, the only option with support. Its support: lesson 275, line 18: «Some historians think ancient people who found Protoceratops skulls in the Gobi Desert imagined griffins, and that mammoth skulls with one big nose hole may ha…», reached through the same lesson line as the sentence the question matched. What matched: the same action «think» (+2); the same doer «historians» (+1). · the question and its options parsed, with trees and pragmatics

Test 10 · wrong ✗

«Lucy's just a monkey, right» What is right?

1. Yes, she was a chimp that lived in a zoo in Africa — ← Mova's choice · no support
2. She was a dinosaur named after a song — no support
3. No, she was an early human relative who walked upright — ✓ the right answer · no support
4. She was a modern woman found in 1974 — no support

Why: Nothing it remembers matched the question, so it guessed: it took the first option shown. · the question and its options parsed, with trees and pragmatics

Test 11 · wrong ✗

Count them: a palaeontologist wraps 4 big bones in plaster jackets and 2 more wait for tomorrow. How many big bones need jackets in all?

1. 4 — ← Mova's choice · score 9
2. 8 — score 9
3. 6 — ✓ the right answer · score 9
4. 2 — score 9

Why: It took the question to ask what it is done to. It chose option 1 with score 9, tied with another option at 9 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 208, line 11: «Some horses need rugs in winter, especially clipped or thin-coated ones, while hardy ponies grow thick coats and may need no rug at all.», reached through the remembered sentence the question matched. What matched: the same place «all» (+8); the same action «need» (+4). Against it: a different thing acted on (counts against) (-1); a different doer (counts against) (-2). The right option, 3, scored 9. · the question and its options parsed, with trees and pragmatics

Exam question 1 · formal language · wrong ✗

Identify the principal condition which renders the fossilisation of an organism more probable.

1. Death at an advanced age — ← Mova's choice · no support
2. Rapid burial in sediment, in the absence of air — ✓ the right answer · no support
3. Prolonged exposure to sunlight upon the surface — no support
4. Consumption of the remains by scavengers — no support

Why: No option found support in what it remembers, so it guessed: it took the first option shown. · the question and its options parsed, with trees and pragmatics

Exam question 2 · formal language · wrong ✗

Which of the following is correctly classified as a trace fossil?

1. A mineralised thigh bone — no support
2. A preserved burrow or footprint — ✓ the right answer · no support
3. A petrified tree trunk — no support
4. An ammonite shell — ← Mova's choice · score 4

Why: It took the question to ask what it is done to. It chose option 4 with score 4, the only option with support. Its support: lesson 275, line 1: «A fossil is a living thing, or a mark it made, that was kept in rock: a shell, a bone, a leaf, a footprint, even a dinosaur's poo.», reached through the option's own match among the sentences about the question's things. What matched: the same circumstance (+3); it fills the role the question asks for (+1). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Exam question 3 · formal language · wrong ✗

Select the response consistent with the established facts concerning the collection of fossils from coastal cliffs.

1. Excavation of cliffs is universally encouraged by authorities — ← Mova's choice · no support
2. All fossils upon beaches are the property of the finder without exception — no support
3. Fossils may lawfully be removed only by persons under ten years of age — no support
4. Excavation of cliffs is hazardous and frequently prohibited, whereas loose specimens may in many places be collected — ✓ the right answer · no support

Why: No option found support in what it remembers, so it guessed: it took the first option shown. · the question and its options parsed, with trees and pragmatics

Exam question 4 · formal language · right ✓

State the significance of the hips and knees of the specimen designated Lucy.

1. They demonstrate that the individual lived in the sea — score 3
2. They demonstrate that the individual could fly short distances — score 3
3. They demonstrate that the individual was a reptile, not a primate — score 3
4. They demonstrate that the individual walked upright — ← Mova's choice · ✓ the right answer · score 4

Why: It took the question to ask which statement is true. It chose option 4 with score 4, against 3 for the next best. Its support: lesson 275, line 19: «Lucy is a 3.2-million-year-old skeleton of a human relative found in Ethiopia in 1974; her hips and knees show she walked upright, and she was named after a Be…», reached through the option's own match among the sentences about the question's things. What matched: the same action «walk» (+3); the same property (+3). Against it: a different doer (counts against) (-2). · the question and its options parsed, with trees and pragmatics

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