One counterexample is enough

Tests: 4 of 12 right · Exam: 2 of 4 right · Kind: ★ · Understood: 10 of 16 · Run: 2026-10-18, commit f3c23ea72

Lesson 187 of the world 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 ✗

The friend: "It's a swan, bro, and it's black. 'All' just died." What is the fair thing for Freddie to say?

1. "OK, not all swans are white." — ✓ the right answer · score 2
2. "Black swans are painted." — score 2
3. "That swan doesn't count, bro." — score 2
4. "One swan proves nothing." — ← Mova's choice · score 6

Why: It took the question to ask which statement is true. It chose option 4 with score 6, against 2 for the next best. Its support: lesson 187, line 2: «Freddie says, "All swans are white." His friend shows a photo of a black swan from Australia. One black swan, and "all" is gone: "It's a swan, bro, and it's bl…», reached through the same lesson line as the sentence the question matched. What matched: the same action «show» (+4); the same doer «friend» (+3). Against it: a different thing acted on (counts against) (-1). The right option, 1, scored 2. · the question and its options parsed, with trees and pragmatics

Test 2 · ★ · wrong ✗

Sophie's brother: "Lionesses won the Euros twice in a row, Sophie. Who's 'can't' now?" What is his point?

1. The Euros don't count — ← Mova's choice · no support
2. Only England's women can play football — no support
3. Boys can't play football — no support
4. One example knocks down "can't", and here there are loads — ✓ 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

Test 3 · ★ · wrong ✗

Leo's sister: "It's literally hopping about on mud, Leo. Fish said 'nah'." What is the better rule?

1. "No fish ever leaves water" — no support
2. "Most fish stay in water" — ✓ the right answer · score 3
3. "Fish only live on mud" — score 3
4. "Mudskippers aren't fish" — ← Mova's choice · 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 187, line 10: «Mudskippers are fish that spend lots of time out of the water, on mud.», reached through the same lesson line as the sentence the question matched. What matched: the same doer «mudskippers» (+3); the same thing acted on «fish» (+3); the same light verb (be, have, do, get, go) (+1). Against it: one says «not», the other does not (counts against) (-3). The right option, 2, scored 3. · the question and its options parsed, with trees and pragmatics

Test 4 · ★ · wrong ✗

Ollie lands his backflip. Ava: "OK, fine, nobody except you." What is Ava doing?

1. Attacking Ollie for showing off — ← Mova's choice · no support
2. Admitting her claim was broken — ✓ the right answer · no support
3. Changing the rules so she can win — no support
4. Proving her claim was right all along — 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 · ★ · wrong ✗

Kai's dad: "The platypus? That thing's a cheat code. Fine, you win." Is "mammals don't lay eggs" still true?

1. Yes; platypuses aren't mammals — score 4
2. No; all mammals lay eggs — ← Mova's choice · score 5
3. No; the platypus breaks it — ✓ the right answer · score 5
4. Yes; one animal doesn't count — no support

Why: It took the question to ask which statement is true. It chose option 2 with score 5, tied with another option at 5 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 187, line 12: «The platypus and the echidnas (spiny anteaters of Australia and New Guinea) are mammals that lay eggs; most mammals give birth to live young.», reached through the option's own match among the sentences about the question's things. What matched: the same action «lay» (+3); the same thing acted on «eggs» (+2). The right option, 3, scored 5. · the question and its options parsed, with trees and pragmatics

Test 6 · ★ · right ✓

Ruby's grandma: "Hates technology, does she? I've got more subscribers than your favourite gamer, darling." What has she broken?

1. The stereotype that every old person hates technology — ← Mova's choice · ✓ the right answer · score 5
2. The rule that gamers have subscribers — no support
3. Her own internet connection — no support
4. The idea that knitting is popular — no support

Why: It took the question to ask what it is done to. It chose option 1 with score 5, the only option with support. Its support: lesson 187, line 13: «Lots of older people use technology well; a rule about everyone of one age is a stereotype.», reached through the same lesson line as the sentence the question matched. What matched: it fills the role the question asks for (+3); the same thing acted on «stereotype» (+2). · the question and its options parsed, with trees and pragmatics

Test 7 · ★ · wrong ✗

Oscar's friend: "Weird or not, it's a dog and it's up a tree. Your rule fell out of the tree." What did Oscar do wrong?

1. He brushed off the counterexample as "weird" — ✓ the right answer · no support
2. He refused to watch the video — score 5
3. He said most dogs can't climb — ← Mova's choice · score 11
4. He counted the dog's legs wrongly in the video — score 1

Why: It took the question to ask what is done. It chose option 3 with score 11, against 5 for the next best. Its support: lesson 187, line 5: «The fix is easy and honest: swap "all" for "most". "Most dogs can't climb trees" is true; "dogs can't climb trees" is not.», reached through the remembered sentence the question matched. What matched: the same doer «most dogs» (+5); it fills the role the question asks for (+4); the same action «climb» (+2). The right option, 1, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 8 · ★ · right ✓

Mia's friend counts a spider's legs: eight. Why does that settle it?

1. Insects always have 6 legs, so a spider isn't one — ← Mova's choice · ✓ the right answer · score 4
2. Legs can't tell you anything — no support
3. Some insects have 8 legs — score 4
4. Spiders lose legs as they grow — score 4

Why: It took the question to ask why something happens (its cause). It chose option 1 with score 4, tied with another option at 4 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 187, line 15: «Spiders are arachnids, not insects: spiders have 8 legs and 2 body parts, insects have 6 legs and 3 body parts.», reached through the same lesson line as the sentence the question matched. What matched: the same doer «insects» (+2); the same thing acted on «6 legs» (+2). · the question and its options parsed, with trees and pragmatics

Test 9 · ★ · right ✓

Finn's mum, 52, skates past: "Over 50, can't skate, he said. Bye, Finn!" Finn: "OK, that's a vibe, Mum." What changed his mind?

1. One clear counterexample — ← Mova's choice · ✓ the right answer · score 7
2. A long argument — score 7
3. Nothing; he's still sure — no support
4. A list of rules — no support

Why: It took the question to ask who or what does it. It chose option 1 with score 7, tied with another option at 7 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 91, line 15: «Scientists change their minds when good new evidence shows they were wrong.», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «minds» (+4); the same action «change» (+3). · the question and its options parsed, with trees and pragmatics

Test 10 · ★ · right ✓

A Scottish gran: "Never rains in summer? Dinnae be daft, hen, it's August and it's chuckin' it doon." What is true?

1. One rainy summer day breaks "never" — ← Mova's choice · ✓ the right answer · no support
2. It never rains in August, whatever she says — no support
3. Summer rain doesn't count — no support
4. It only rains in Scotland — 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 11 · ★ · wrong ✗

The teacher: "Mercury: a metal, and runny. Don't touch it, it's poisonous." Which claim does mercury break?

1. "All metals are shiny" — no support
2. "Metals carry electricity" — score 3
3. "Metals are found in rocks" — ← Mova's choice · score 7
4. "All metals are hard" — ✓ the right answer · no support

Why: It took the question to ask who or what does it. It chose option 3 with score 7, against 3 for the next best. Its support: lesson 187, line 6: «One clear example that breaks an "all", "never" or "nobody" claim shows the claim is false.», reached through the same lesson line as the sentence the question matched. What matched: it fills the role the question asks for (+4); the same doer «claim» (+3). The right option, 4, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 12 · ★ · wrong ✗

In a cartoon a scientist sees one purple cow and shouts, "So ALL cows are purple!" What is the mistake?

1. One example always proves "all" — no support
2. One example can break "all", but it can't prove "all" — ✓ the right answer · no support
3. Cows can't be purple in cartoons — no support
4. Scientists never look at cows — ← Mova's choice · score 1

Why: It took the question to ask which statement is true. It chose option 4 with score 1, the only option with support. Its support: lesson 78, line 5: «By looking at a fossil skull, scientists can tell what an animal ate: Tyrannosaurus had long, sharp, curved teeth for meat, while Triceratops had a beak and ro…», reached through the option's own match among the sentences about the question's things. What matched: the same action «look» (+3). Against it: one says «not», the other does not (counts against) (-2). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Exam question 1 · formal language · right ✓

Identify the minimum number of counterexamples required to demonstrate that a claim concerning all members of a group is false.

1. One — ← Mova's choice · ✓ the right answer · no support
2. Two — no support
3. All members of the group — no support
4. Ten — 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 ✗

It is given that black swans are found in Australia. Select the response consistent with the established facts concerning the assertion that all swans are white.

1. The assertion remains true — ← Mova's choice · no support
2. The assertion is false — ✓ the right answer · no support
3. The assertion is true of Australian swans only — no support
4. No conclusion may be drawn — 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 3 · formal language · right ✓

Which of the following statements most accurately characterises the dismissal of a counterexample on the ground that it is "weird"?

1. It leaves the counterexample in force and the claim refuted — ← Mova's choice · ✓ the right answer · score 6
2. It proves the original claim conclusively — no support
3. It constitutes a second counterexample — no support
4. It restores the original claim to truth — no support

Why: It took the question to ask who or what does it. It chose option 1 with score 6, the only option with support. Its support: lesson 187, line 8: «Saying a counterexample "doesn't count" or is "weird" doesn't make it go away; grown-ups call this the "no true Scotsman" move.», reached through the same lesson line as the sentence the question matched. What matched: it fills the role the question asks for (+4); the same doer «counterexample» (+3). Against it: a different action (counts against) (-1). · the question and its options parsed, with trees and pragmatics

Exam question 4 · formal language · wrong ✗

Ascertain which of the following animals constitutes a mammal that lays eggs.

1. The dolphin — ← Mova's choice · no support
2. The platypus — ✓ the right answer · no support
3. The bat — no support
4. The kangaroo — 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

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