Materials and their properties

Tests: 7 of 13 right · Exam: 2 of 4 right · Kind: ★★ · Understood: 10 of 17 · Run: 2026-10-18, commit f3c23ea72

Lesson 18 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 cook leaves a metal spoon and a plastic spoon in a pot of hot stew. Which handle gets hot?

1. Neither of them — ← Mova's choice · no support
2. The plastic one — no support
3. The metal one — ✓ the right answer · no support
4. Both get equally hot — 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 2 · ★★ · wrong ✗

Why do birds fluff out their feathers on a frosty day?

1. To make their feathers dry faster — ← Mova's choice · no support
2. To trap more air, which insulates them — ✓ the right answer · no support
3. To catch the warm wind — no support
4. To let the cold air reach right down to their skin — 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 3 · ★★ · right ✓

A ball of plasticine sinks, but the same plasticine pressed into a boat shape floats. Why?

1. The boat shape pushes aside enough water to hold it up — ← Mova's choice · ✓ the right answer · score 6
2. The water under the boat is warmer — no support
3. The plasticine became lighter — no support
4. Boats can only float on salty water — no support

Why: It took the question to ask why something happens (its cause). It chose option 1 with score 6, the only option with support. Its support: lesson 18, line 3: «An object floats if it is less dense than the water: it has less mass than the same amount of water would have. A steel ship floats because its hollow shape is…», reached through the option's own match among the sentences about the question's things. What matched: the same action «push» (+3); the same doer «hollow shape» (+2); the same property (+1). · the question and its options parsed, with trees and pragmatics

Test 4 · ★★ · right ✓

Which is true about salt dissolved in water?

1. The salt has been destroyed — no support
2. The salt has turned into water — score 5
3. The salt is still in the water — ← Mova's choice · ✓ the right answer · score 6
4. The salt has floated away as a gas — no support

Why: It took the question to ask which statement is true. It chose option 3 with score 6, against 5 for the next best. Its support: lesson 18, line 4: «Some solids dissolve in water: sugar and salt break up into particles too small to see and spread through the water, making a solution. Sand and pepper do not…», reached through the same lesson line as the sentence the question matched. What matched: the same doer «sugar» (+4); the same place «water» (+2). · the question and its options parsed, with trees and pragmatics

Test 5 · ★★ · wrong ✗

Why are picnic cool boxes made with a thick layer of foam?

1. Foam is heavy and holds the lid down — ← Mova's choice · no support
2. Foam lets heat through quickly — no support
3. Foam makes cold of its own — no support
4. Foam is full of trapped air and insulates — ✓ 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 6 · ★★ · right ✓

How can you get salt back from salty water?

1. Pour it through filter paper — no support
2. Pour it through a sieve — no support
3. Let the water evaporate — ← Mova's choice · ✓ the right answer · score 4
4. Stir it very fast — no support

Why: It took the question to ask what something is like. It chose option 3 with score 4, the only option with support. Its support: lesson 18, line 16: «Dissolving can be reversed: you can get salt back by letting the water evaporate.», reached through a sentence linked to the one the question matched. What matched: the same action «let» (+2); the same thing acted on «water» (+2). · the question and its options parsed, with trees and pragmatics

Test 7 · ★★ · wrong ✗

A builder puts a thick fluffy layer of insulation in a roof. What is it for?

1. To make the roof heavier in the wind — ← Mova's choice · no support
2. To stop heat escaping from the house in winter — ✓ the right answer · no support
3. To make the rooms brighter — no support
4. To make the roof waterproof — 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 · ★★ · right ✓

An apple floats but a raw potato of the same size usually sinks. Why?

1. The apple is lighter in colour — no support
2. The potato is rounder in shape — no support
3. The apple is less dense, partly because of the air inside it — ← Mova's choice · ✓ the right answer · score 6
4. The apple has a stalk at the top that holds it up in the water — no support

Why: It took the question to ask why something happens (its cause). It chose option 3 with score 6, the only option with support. Its support: lesson 18, line 3: «An object floats if it is less dense than the water: it has less mass than the same amount of water would have. A steel ship floats because its hollow shape is…», reached through the cause of the sentence the question matched. What matched: the same circumstance (+4); the same light verb (be, have, do, get, go) (+3). Against it: a different doer (counts against) (-1). · the question and its options parsed, with trees and pragmatics

Test 9 · ★★ · right ✓

Which will dissolve in a glass of warm water?

1. Cooking oil — no support
2. Sand — score 4
3. Salt — ← Mova's choice · ✓ the right answer · score 10
4. Small pebbles — score 3

Why: It took the question to ask who or what does it. It chose option 3 with score 10, against 4 for the next best. Its support: lesson 18, line 4: «Some solids dissolve in water: sugar and salt break up into particles too small to see and spread through the water, making a solution. Sand and pepper do not…», 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 action «break up» (+3); the same doer «sugar» (+3). · the question and its options parsed, with trees and pragmatics

Test 10 · ★★ · right ✓

why's the metal spoon in my tea so hot but not the wooden one

1. The metal spoon makes its own heat — no support
2. Metal is a good conductor of heat, wood is not — ← Mova's choice · ✓ the right answer · score 3
3. Tea only heats up shiny things — no support
4. Wood is a good conductor of heat — 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 18, line 5: «For example, a metal spoon left in hot tea soon has a hot handle, but a wooden spoon does not, because metal conducts heat and wood insulates.», reached through a sentence linked to the one the question matched. What matched: the same doer «metal» (+2); the same circumstance (+2). Against it: a different thing acted on (counts against) (-1). · the question and its options parsed, with trees and pragmatics

Test 11 · ★★ · right ✓

will sugar dissolve quicker in hot tea or cold

1. It won't dissolve in either — score 1
2. In hot tea — ← Mova's choice · ✓ the right answer · score 3
3. In cold tea — no support
4. Just the same in both — no support

Why: It took the question to ask which statement is true. It chose option 2 with score 3, against 1 for the next best. Its support: lesson 18, line 5: «For example, a metal spoon left in hot tea soon has a hot handle, but a wooden spoon does not, because metal conducts heat and wood insulates.», reached through the option's own match among the sentences about the question's things. What matched: the same place «hot tea» (+2); the same property (+1). · the question and its options parsed, with trees and pragmatics

Test 12 · ★★ · wrong ✗

Leo says a coat keeps u warm cos it makes heat. true?

1. Yes, wool makes heat when you wear it — ← Mova's choice · score 4
2. Yes, coats warm up in the sunshine and keep it — no support
3. No, it keeps you warm by keeping out the light — score 4
4. No, it slows the loss of your own body heat — ✓ the right answer · score 3

Why: It took the question to ask which statement is true. 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 5, line 1: «The Sun is a star: a gigantic ball of very hot gas that makes its own light and heat.», reached through the remembered sentence the question matched. What matched: the same action «make» (+4); the same thing acted on «own light» (+2). Against it: a different doer (counts against) (-2). The right option, 4, scored 3. · the question and its options parsed, with trees and pragmatics

Test 13 · ★★ · wrong ✗

Tom reckons heavy things always sink. right?

1. No, heavy things always float — ← Mova's choice · score 6
2. Yes, ships float only because they are light — no support
3. No, it depends on material and shape, not weight alone — ✓ the right answer · score 6
4. Yes, anything heavy goes to the bottom — no support

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 18, line 12: «Whether an object floats depends on its material and its shape, not on its weight alone; things with air inside them, like an apple, are less dense and float m…», reached through the remembered sentence the question matched. What matched: the same action «float» (+4); the same doer «things» (+2). The right option, 3, scored 6. · the question and its options parsed, with trees and pragmatics

Exam question 1 · formal language · wrong ✗

Identify, from among the following, the material that conducts heat most effectively.

1. Dry wood — ← Mova's choice · no support
2. Natural cork — no support
3. Woollen cloth — no support
4. Metal — ✓ 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 2 · formal language · wrong ✗

Which of the following statements most accurately characterises the function of a warm coat?

1. It generates heat of its own — ← Mova's choice · no support
2. It admits the heat of the Sun — no support
3. It draws warmth from the surrounding air — no support
4. It retards the loss of the wearer's own body heat — ✓ 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 3 · formal language · right ✓

Identify the determining condition by which an object floats upon water.

1. Its being less dense than water — ← Mova's choice · ✓ the right answer · score 3
2. Its being of small dimensions — no support
3. Its being composed of wood alone — no support
4. Its being light in weight alone — no support

Why: It took the question to ask which statement is true. It chose option 1 with score 3, the only option with support. Its support: lesson 12, line 17: «High up in the mountains water boils below 100 °C, because the air pressure there is lower: the air is thinner and presses down less on the water.», reached through the option's own match among the sentences about the question's things. What matched: the same circumstance (+2); the same property (+1). · the question and its options parsed, with trees and pragmatics

Exam question 4 · formal language · right ✓

It is given that 10 grams of sugar is dissolved in 100 grams of water. Ascertain the mass of the resulting solution.

1. One hundred and ten grams — ← Mova's choice · ✓ the right answer · no support
2. Precisely one hundred grams — no support
3. Ten grams, being the sugar alone — no support
4. Ninety grams, the sugar having vanished — 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

This page in Markdown → https://md.mova.elamur.ai/free/en/school-run/world/18-materials-and-properties/