Static electricity: balloons, hair and sparks

Tests: 6 of 11 right · Exam: 1 of 4 right · Kind: plain · Understood: 11 of 15 · Run: 2026-10-18, commit f3c23ea72

Lesson 26 of the physics 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 · right ✓

Nan says lightning never strikes the same place twice, so the spot where it hit is safe now. right?

1. Yes, but only for a year — no support
2. No, lightning often hits the same tall place again and again — ← Mova's choice · ✓ the right answer · score 8
3. No, it strikes exactly twice and then stops — no support
4. Yes, it can never strike there again — 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 26, line 14: «Lightning often strikes the same tall place again and again; the Empire State Building in New York is hit around twenty times a year.», reached through the option's own match among the sentences about the question's things. What matched: the same action «strike» (+3); the same thing acted on «same tall place» (+3); the same doer «lightning» (+2). · the question and its options parsed, with trees and pragmatics

Test 2 · right ✓

A thin stream of water from the tap bends towards a rubbed comb. What does this show?

1. The charged comb pulls on the water — ← Mova's choice · ✓ the right answer · no support
2. The water has partly frozen into ice — no support
3. The comb blows a little air at the water — no support
4. The comb has turned into a small magnet — 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 ✗

argh, every time I touch the car door I get zapped. why's it worse in winter?

1. Your coat is wired to the car — ← Mova's choice · score 1
2. Cold metal makes its own electricity in winter — no support
3. Dry winter air lets charge build up on you — ✓ the right answer · no support
4. The car is plugged in during winter — score 1

Why: It took the question to ask why something happens (its cause). It chose option 1 with score 1, tied with another option at 1 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 19, line 15: «A slammed door bangs because it hits the frame and pushes the air away suddenly; a soft rubber strip on the frame makes it quieter.», reached through the cause of the sentence the question matched. What matched: the same doer «door» (+2); a different action (counts against) (+1). Against it: a different thing acted on (counts against) (-2). The right option, 3, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 4 · wrong ✗

In a cartoon, lightning hits a character, who only gets sooty hair and a funny face. What is the truth?

1. Lightning only tickles — no support
2. Lightning cannot hit people — score 2
3. Lightning is a giant spark that can kill, far hotter than the Sun's surface — ✓ the right answer · no support
4. Lightning only makes hair curly — ← Mova's choice · score 5

Why: It took the question to ask which statement is true. It chose option 4 with score 5, against 2 for the next best. Its support: lesson 26, line 15: «Lightning forms when ice and water bumping in a storm cloud build up huge charges that jump to the ground as a giant spark.», reached through the option's own match among the sentences about the question's things. What matched: the same action «form» (+3); the same doer «lightning» (+2). The right option, 3, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 5 · wrong ✗

What would happen if a tall church had no lightning rod and was struck?

1. Nothing, churches cannot be struck — score -3
2. The lightning could pass through the building and damage it — ✓ the right answer · no support
3. The lightning would bounce straight back up into the storm cloud — ← Mova's choice · score 4
4. The church would store the charge for ever — no support

Why: It took the question to ask what happens next. It chose option 3 with score 4, against -3 for the next best. Its support: lesson 5, line 10: «A trampoline's springs and mat stretch as you land and spring back, and most trampoline injuries happen when two people bounce at once.», reached through what followed the sentence the question matched. What matched: the same action «bounce» (+5). Against it: a different doer (counts against) (-1). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 6 · wrong ✗

Which is true about a crackling jumper and a bolt of lightning?

1. They have nothing at all in common — no support
2. A jumper's crackle is only a sound from the wool, with no spark at all — ← Mova's choice · score 5
3. Lightning is made of wool fibres — no support
4. Both are sparks from built-up charge, one tiny and one huge — ✓ the right answer · no support

Why: It took the question to ask which statement is true. It chose option 2 with score 5, the only option with support. Its support: lesson 26, line 11: «A jumper crackles and sparks in the dark when you take it off, because rubbing fabrics build up charge and each crackle is a tiny spark.», reached through the option's own match among the sentences about the question's things. What matched: the same action «crackle» (+3); the same doer «jumper» (+2). The right option, 4, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 7 · wrong ✗

Your clothes dried on the washing line outside never cling. Why?

1. The Sun makes them magnetic — no support
2. They were not rubbed and charged by tumbling — ✓ the right answer · no support
3. Clothes only ever cling in summer, when it is hot — ← Mova's choice · score 6
4. The wind glued them apart — 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 26, line 12: «Clothes stick together after the tumble dryer because tumbling charges them, while clothes dried on a line in open air hardly ever cling, and a dryer sheet tum…», reached through the same lesson line as the sentence the question matched. What matched: the same action «cling» (+4); the same doer «clothes» (+2). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 8 · right ✓

bet u can't stick this balloon on the ceiling without tape. How could you do it?

1. Rub it on your hair and hold it up to the ceiling — ← Mova's choice · ✓ the right answer · score 12
2. Paint it with glitter — no support
3. Fill it with water — score 3
4. Freeze it first — no support

Why: It took the question to ask what something is like. It chose option 1 with score 12, against 3 for the next best. Its support: lesson 26, line 2: «Rub a balloon on your hair and electrons move from your hair to the balloon; opposite charges pull, so your hair reaches for the balloon, while hairs with the…», reached through the remembered sentence the question matched. What matched: the same action «rub» (+5); the same place «hair» (+4); the same thing acted on «balloon» (+3). · the question and its options parsed, with trees and pragmatics

Test 9 · right ✓

Two balloons both rubbed on your hair hang side by side on strings. What do they do?

1. Pop at once — no support
2. Push away from each other, because they have the same charge — ← Mova's choice · ✓ the right answer · score 4
3. Snap together tightly — no support
4. Hang touching, doing nothing — no support

Why: It took the question to ask what is done. It chose option 2 with score 4, the only option with support. Its support: lesson 26, line 6: «Rubbing a balloon on your hair moves electrons onto the balloon, so the balloon and your hair carry opposite charges and pull on each other.», reached through the same lesson line as the sentence the question matched. What matched: the same doer «balloon» (+2); the same thing acted on «opposite charges» (+2). · the question and its options parsed, with trees and pragmatics

Test 10 · right ✓

Why is it a bad idea to stand on a hilltop or under a lone tall tree in a thunderstorm?

1. Lightning tends to strike tall, high things — ← Mova's choice · ✓ the right answer · no support
2. Wind is stronger under trees — no support
3. Hills attract hail only, and hail can be deadly — no support
4. Trees catch fire from rain — 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 · right ✓

Why do dryer sheets help stop static cling?

1. They stop charge building up on the clothes — ← Mova's choice · ✓ the right answer · score 4
2. They make the dryer hotter — no support
3. They glue the clothes apart — no support
4. They make the clothes heavier so they cannot cling — no support

Why: It took the question to ask why something happens (its cause). It chose option 1 with score 4, the only option with support. Its support: lesson 26, line 12: «Clothes stick together after the tumble dryer because tumbling charges them, while clothes dried on a line in open air hardly ever cling, and a dryer sheet tum…», reached through the option's own match among the sentences about the question's things. What matched: the same action «stop» (+3); the same doer «dryer sheet» (+1). · the question and its options parsed, with trees and pragmatics

Exam question 1 · formal language · wrong ✗

Identify the principal process whereby a rubber balloon acquires an electric charge upon being rubbed against hair.

1. The creation of new charge within the rubber by the heat of friction — ← Mova's choice · no support
2. The absorption of air by the hair — no support
3. The magnetisation of the rubber — no support
4. The transfer of electrons from the hair to the balloon — ✓ 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 · right ✓

Which of the following statements most accurately characterises the behaviour of two bodies bearing like charges?

1. They attract one another — no support
2. They exchange their charges instantaneously — no support
3. They exert no influence upon one another — no support
4. They repel one another — ← Mova's choice · ✓ the right answer · score 7

Why: It took the question to ask who or what does it. It chose option 4 with score 7, the only option with support. Its support: lesson 14, line 7: «The air presses on every surface from all sides, and we do not feel it because our body pushes back just as hard.», reached through the option's own match among the sentences about the question's things. What matched: it fills the role the question asks for (+3); the same action «push back» (+2); the same doer «body» (+2). · the question and its options parsed, with trees and pragmatics

Exam question 3 · formal language · wrong ✗

It is asserted that lightning does not strike the same location on more than one occasion. Select the response that is consistent with the established facts.

1. Tall structures are struck repeatedly, some many times within a single year — ✓ the right answer · score 4
2. Lightning strikes each location exactly twice — ← Mova's choice · score 5
3. Lightning never strikes structures of great height — score 2
4. The assertion is correct without exception — no support

Why: It took the question to ask which statement is true. It chose option 2 with score 5, against 4 for the next best. Its support: lesson 26, line 14: «Lightning often strikes the same tall place again and again; the Empire State Building in New York is hit around twenty times a year.», reached through the option's own match among the sentences about the question's things. What matched: the same action «strike» (+3); the same doer «lightning» (+2). The right option, 1, scored 4. · the question and its options parsed, with trees and pragmatics

Exam question 4 · formal language · wrong ✗

Ascertain the function of a lightning conductor affixed to a tall building.

1. To amplify the discharge in order to protect adjacent buildings — ← Mova's choice · no support
2. To repel thunderclouds from the vicinity — no support
3. To attract a greater number of discharges for storage — no support
4. To provide a path of low resistance whereby the discharge is conveyed safely to earth — ✓ 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

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