Clever reasoning about water and matter

Tests: 6 of 13 right · Exam: 3 of 4 right · Kind: ★★★ · Understood: 14 of 17 · Run: 2026-10-18, commit f3c23ea72

Lesson 20 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 ✗

A sealed plastic bottle filled to the top with water is put in the freezer. What happens?

1. It bulges or splits as the ice expands — ✓ the right answer · score 2
2. The water stays liquid because the bottle is sealed — ← Mova's choice · score 5
3. Nothing changes at all — no support
4. It is squeezed inward as the water shrinks — no support

Why: It took the question to ask what happens next. It chose option 2 with score 5, against 2 for the next best. Its support: lesson 20, line 2: «Because ice floats, a pond freezes from the top down. The ice lid insulates the water below, which stays liquid, so fish and frogs can survive the winter at th…», reached through the same lesson line as the sentence the question matched. What matched: the same action «stay» (+2); the same doer «water» (+2); the same property (+1). The right option, 1, scored 2. · the question and its options parsed, with trees and pragmatics

Test 2 · ★★★ · wrong ✗

A girl says, "My glass of cold lemonade is leaking, it is wet outside." What would show she is wrong?

1. Wiping the glass dries it for a moment — ← Mova's choice · score 4
2. Pouring the lemonade into a bigger glass — no support
3. Adding more ice makes it wetter — no support
4. An empty cold sealed jar beside it gets wet too — ✓ the right answer · no support

Why: It took the question to ask what it is done to. It chose option 1 with score 4, the only option with support. Its support: lesson 20, line 3: «A cold glass gets wet on the outside because water vapour in the warm air touches the cold glass, cools and condenses: the water comes from the air, not throug…», reached through a sentence linked to the one the question matched. What matched: it fills the role the question asks for (+3); the same thing acted on «cold glass» (+2). Against it: a different action (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 3 · ★★★ · wrong ✗

If ice were denser than water, what might happen to pond life in a long hard winter?

1. Nothing would change for them — ← Mova's choice · no support
2. Ponds could freeze solid and many animals would die — ✓ the right answer · no support
3. Fish could swim up and live on top of the ice instead — no support
4. Ponds would never freeze over — 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 4 · ★★★ · right ✓

How can salt melt the ice on a road at -5 °C?

1. Salty water freezes below -5 °C, so it stays liquid — ← Mova's choice · ✓ the right answer · score 6
2. Salt is a fuel that slowly burns — no support
3. Salt heats the ice up to 0 °C — no support
4. Car tyres warm the salt up — no support

Why: It took the question to ask what something is like. It chose option 1 with score 6, the only option with support. Its support: lesson 20, line 4: «Salt is spread on icy roads because salty water freezes at a lower temperature than pure water; the salt dissolves in the thin wet layer on the ice and makes i…», reached through the same lesson line as the sentence the question matched. What matched: the same action «freeze» (+3); the same doer «salty water» (+3). · the question and its options parsed, with trees and pragmatics

Test 5 · ★★★ · right ✓

In the same cold weather, a lake freezes over but the sea beside it does not freeze. What is the best explanation?

1. Seawater is always warmer from the Sun — no support
2. Seawater is salty and freezes at a lower temperature — ← Mova's choice · ✓ the right answer · score 6
3. Fish in the sea keep the water warm — score 6
4. Seawater is heavier than lake water, so it cannot freeze — no support

Why: It took the question to ask what it is done to. It chose option 2 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 20, line 4: «Salt is spread on icy roads because salty water freezes at a lower temperature than pure water; the salt dissolves in the thin wet layer on the ice and makes i…», reached through the remembered sentence the question matched. What matched: the same action «freeze» (+4); the same place «lower temperature» (+4). Against it: a different doer (counts against) (-2). · the question and its options parsed, with trees and pragmatics

Test 6 · ★★★ · wrong ✗

Why does a pond freeze first at the top and not at the bottom?

1. Ice sinks and piles up from the bottom — ← Mova's choice · score 5
2. Frogs on the bottom melt the ice there — no support
3. The Sun warms only the top of the pond — no support
4. The surface touches the cold air, and ice floats — ✓ the right answer · no support

Why: It took the question to ask why something happens (its cause). It chose option 1 with score 5, the only option with support. Its support: lesson 20, line 2: «Because ice floats, a pond freezes from the top down. The ice lid insulates the water below, which stays liquid, so fish and frogs can survive the winter at th…», reached through the cause of the sentence the question matched. What matched: the same doer «ice» (+5). The right option, 4, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 7 · ★★★ · wrong ✗

Ice cubes float in a glass of water filled exactly to the brim. What happens as they melt?

1. It overflows only if the cubes were big — ← Mova's choice · no support
2. The water level stays about the same and it does not overflow — ✓ the right answer · no support
3. It overflows, because the ice turns into more water — no support
4. The level drops well below the brim — 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 ✗

Why does a mountain hut buried under deep snow stay warmer inside than the frosty air?

1. The snow traps air and insulates the hut — ✓ the right answer · score 2
2. Snow is made of warm water — no support
3. The snow pulls the cold out of the walls — no support
4. The snow makes heat as it sits there — ← Mova's choice · score 3

Why: It took the question to ask why something happens (its cause). It chose option 4 with score 3, against 2 for the next best. Its support: lesson 15, line 11: «Snow forms when water freezes into ice crystals inside a cold cloud.», reached through the option's own match among the sentences about the question's things. What matched: the same action «form» (+2); the same doer «snow» (+1). The right option, 1, scored 2. · the question and its options parsed, with trees and pragmatics

Test 9 · ★★★ · right ✓

Why does your breath make a white cloud on a frosty day but not on a warm day?

1. Cold air freezes your breath at once and turns it into tiny flakes of snow — no support
2. In winter breath has smoke in it — no support
3. Cold air cools the vapour in your breath so it condenses into droplets — ← Mova's choice · ✓ the right answer · score 5
4. In summer we breathe out no water at all — no support

Why: It took the question to ask why something happens (its cause). It chose option 3 with score 5, the only option with support. Its support: lesson 14, line 3: «As the moist air rises it cools, and the vapour condenses on tiny specks of dust, smoke and sea salt into droplets that make clouds.», reached through the same lesson line as the sentence the question matched. What matched: the same doer «air» (+3); the same action «cool» (+2). · the question and its options parsed, with trees and pragmatics

Test 10 · ★★★ · right ✓

why do ice cubes float in ur drink

1. Ice is lighter because it is cold — no support
2. Ice is less dense than liquid water — ← Mova's choice · ✓ the right answer · score 8
3. Ice has air bubbles that make it a gas — no support
4. The drink pushes all solids to the top — no support

Why: It took the question to ask which statement is true. It chose option 2 with score 8, the only option with support. Its support: lesson 20, line 1: «Most liquids shrink when they freeze, but water is unusual: it expands, so ice is less dense than water and floats.», reached through the same lesson line as the sentence the question matched. What matched: the same doer «ice» (+4); the same circumstance (+2); the same property (+1); the same light verb (be, have, do, get, go) (+1). · the question and its options parsed, with trees and pragmatics

Test 11 · ★★★ · right ✓

if the ice in my glass melts will it overflow

1. Yes, it will spill over the top — no support
2. No, the level drops a lot — no support
3. Yes, melted ice makes much more water — score 1
4. No, the level hardly changes — ← Mova's choice · ✓ the right answer · score 7

Why: It took the question to ask which statement is true. It chose option 4 with score 7, against 1 for the next best. Its support: lesson 20, line 15: «When floating ice melts, the water level hardly changes, because the ice was already pushing aside its own weight of water.», reached through a sentence linked to the one the question matched. What matched: the same action «change» (+3); the same doer «water level» (+2); the same property (+2). · the question and its options parsed, with trees and pragmatics

Test 12 · ★★★ · right ✓

Leo says the drops on a cold glass leak through from inside. true?

1. Yes, cold glass lets water through — no support
2. Yes, the drink sweats through tiny holes — no support
3. No, they come from water vapour in the air — ← Mova's choice · ✓ the right answer · score 10
4. No, they come from the ice melting outside — score 6

Why: It took the question to ask which statement is true. It chose option 3 with score 10, against 6 for the next best. Its support: lesson 20, line 12: «The drops on the outside of a cold glass come from water vapour in the air.», reached through the remembered sentence the question matched. What matched: the same action «come» (+4); the same place «water vapour» (+4); the same doer «drops» (+2). · the question and its options parsed, with trees and pragmatics

Test 13 · ★★★ · wrong ✗

my brother says road salt melts ice however cold it is. right?

1. No, in very hard frost even salty water freezes — ✓ the right answer · no support
2. No, salt only works on snow, not ice — no support
3. Yes, the colder it is the better salt works — no support
4. Yes, salt melts ice at any temperature — ← Mova's choice · score 6

Why: It took the question to ask which statement is true. It chose option 4 with score 6, the only option with support. Its support: lesson 20, line 4: «Salt is spread on icy roads because salty water freezes at a lower temperature than pure water; the salt dissolves in the thin wet layer on the ice and makes i…», reached through the remembered sentence the question matched. What matched: the same action «dissolve» (+4); the same doer «salt» (+2). The right option, 1, 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 principal reason for which ice floats upon liquid water.

1. Ice contains trapped air and nothing else — score 1
2. Ice is warmer than the liquid water beneath — score 4
3. Ice is less dense than liquid water — ← Mova's choice · ✓ the right answer · score 5
4. Ice is heavier than the liquid water below it — score 4

Why: It took the question to ask which statement is true. It chose option 3 with score 5, against 4 for the next best. Its support: lesson 20, line 7: «Ice is less dense than liquid water, so it floats.», reached through the option's own match among the sentences about the question's things. What matched: the same circumstance (+2); the same doer «ice» (+1); the same property (+1); the same light verb (be, have, do, get, go) (+1). · the question and its options parsed, with trees and pragmatics

Exam question 2 · formal language · right ✓

It is given that a lake freezes at its surface in winter. Ascertain the usual temperature of its deepest water.

1. Approximately four degrees Celsius — ← Mova's choice · ✓ the right answer · no support
2. Zero degrees Celsius, like the ice above — no support
3. Twenty degrees Celsius, as in summer — no support
4. Minus ten degrees Celsius, or colder still — 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 · wrong ✗

Select the response that is consistent with the established facts concerning the drops upon the exterior of a cold glass.

1. They have passed through the wall of the glass — no support
2. They derive from water vapour present in the surrounding air — ✓ the right answer · no support
3. They have splashed from the beverage within — no support
4. They have been produced by the cold itself — ← Mova's choice · score 6

Why: It took the question to ask which statement is true. It chose option 4 with score 6, the only option with support. Its support: lesson 14, line 11: «A cloud is made of millions of tiny water drops, or of tiny ice crystals where it is very cold.», reached through the remembered sentence the question matched. What matched: the same action «make» (+4); the same thing acted on «cloud» (+2). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Exam question 4 · formal language · right ✓

Whereas floating ice melts in a glass of water, determine the effect upon the water level.

1. It invariably overflows the rim of the vessel — no support
2. It falls markedly as the ice disappears — no support
3. It remains approximately unaltered — ← Mova's choice · ✓ the right answer · score 8
4. It rises markedly as the ice turns to water — score 2

Why: It took the question to ask which statement is true. It chose option 3 with score 8, against 2 for the next best. Its support: lesson 12, line 10: «While ice is melting, it stays at 0 °C until all of it has melted.», reached through the same lesson line as the sentence the question matched. What matched: the same action «stay» (+4); the same doer «ice» (+4). · the question and its options parsed, with trees and pragmatics

This page in Markdown → https://md.mova.elamur.ai/free/en/school-run/world/20-reasoning-water-and-matter/