Stars: what they are

Tests: 7 of 11 right · Exam: 2 of 4 right · Kind: ★ · Understood: 10 of 15 · Run: 2026-10-18, commit f3c23ea72

Lesson 17 of the space 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 ✓

My little sister says the Sun isn't a star cos stars are tiny and come out at night. what do you tell her

1. She is right, the Sun is a planet — score 7
2. The Sun is a star; the others just look tiny because they are so far away — ← Mova's choice · ✓ the right answer · score 9
3. Stars only shine at night, so the Sun can't be one — score 9
4. The Sun is a star that is smaller than all the others — score 9

Why: It took the question to ask which statement is true. It chose option 2 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 1, line 1: «The Sun is a star, the same kind of thing as the tiny dots you see at night, only so close that it fills our day with light.», reached through the remembered sentence the question matched. What matched: the same doer «sun» (+4); the same thing acted on «star» (+3); the same light verb (be, have, do, get, go) (+2). · the question and its options parsed, with trees and pragmatics

Test 2 · ★ · wrong ✗

In a cartoon a star has five points and a smiley face. What does a real star look like up close?

1. A flat disc of ice — ← Mova's choice · no support
2. A huge round ball of glowing gas — ✓ the right answer · no support
3. A tiny spark like a firework — no support
4. A five-pointed piece of shiny rock — 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 · ★ · right ✓

A star glows blue-white and another glows red. Which is hotter?

1. The blue-white one — ← Mova's choice · ✓ the right answer · score 5
2. The red one — score 3
3. You cannot tell anything from colour — no support
4. They are both the same — no support

Why: It took the question to ask which statement is true. It chose option 1 with score 5, against 3 for the next best. Its support: lesson 17, line 10: «Star colours show their temperature: red stars are coolest at about 3,000 °C, the Sun is yellow-white at about 5,500 °C, and blue-white stars can be over 20,00…», reached through the remembered sentence the question matched. What matched: the same doer «white stars» (+4); the same property (+1). · the question and its options parsed, with trees and pragmatics

Test 4 · ★ · right ✓

Why can you see far more stars in the countryside than in the city?

1. There really are more stars above the countryside than towns — score 4
2. Town lights make the sky too bright to see faint stars — ← Mova's choice · ✓ the right answer · score 12
3. City air has no stars in it — score 0
4. Stars avoid shining on cities — score 5

Why: It took the question to ask why something happens (its cause). It chose option 2 with score 12, against 5 for the next best. Its support: lesson 17, line 15: «On a very dark, clear night away from towns, you can see about 2,000 to 3,000 stars at once with the naked eye, but in a city only a few dozen, because street…», reached through the cause of the sentence the question matched. What matched: the same action «make» (+4); the same doer «street lights» (+4); the same thing acted on «sky» (+4). · the question and its options parsed, with trees and pragmatics

Test 5 · ★ · right ✓

are you thick or what, Sirius is obviously the closest star cos it's brightest. right?

1. No, Sirius is not a star but a planet — score 9
2. Yes, Sirius is closer than the Sun — score 7
3. No, it is bright because it is powerful and fairly near; the Sun and others are closer — ← Mova's choice · ✓ the right answer · score 11
4. Yes, the brightest star is always the closest — score 7

Why: It took the question to ask which statement is true. It chose option 3 with score 11, against 9 for the next best. Its support: lesson 17, line 12: «Most stars in our galaxy are red dwarfs, smaller, cooler and dimmer than the Sun, and not one of them is bright enough to see with the naked eye.», reached through the remembered sentence the question matched. What matched: the same doer «one» (+4); its «because» matches the remembered cause (+4); the same light verb (be, have, do, get, go) (+2); the same property (+1). · the question and its options parsed, with trees and pragmatics

Test 6 · ★ · right ✓

If you looked at the stars from the Moon, which has no air, would they twinkle?

1. No, you could not see any stars at all — score 3
2. Yes, exactly the same as from the Earth — no support
3. Yes, even more than from the Earth — no support
4. No, with no air to bend the light they would shine steadily — ← 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, against 3 for the next best. Its support: lesson 16, line 1: «A shooting star is not a star at all: it is a grain of rock or dust, often smaller than a grain of sand, rushing into the Earth's air so fast that it glows and…», 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 «glow» (+2); the same doer «star» (+2). · the question and its options parsed, with trees and pragmatics

Test 7 · ★ · wrong ✗

Most stars in the galaxy are red dwarfs. Why can't we see any of them without a telescope?

1. They only shine in the daytime — ← Mova's choice · score 5
2. They are hidden behind the Sun — score 2
3. They are black and give no light — score 4
4. They are all too dim — ✓ the right answer · score 5

Why: It took the question to ask why something happens (its cause). It chose option 1 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 16, line 1: «A shooting star is not a star at all: it is a grain of rock or dust, often smaller than a grain of sand, rushing into the Earth's air so fast that it glows and…», reached through the option's own match among the sentences about the question's things. What matched: the same doer «star» (+3); the same action «glow» (+2). The right option, 4, scored 5. · the question and its options parsed, with trees and pragmatics

Test 8 · ★ · wrong ✗

Which is true?

1. Stars never orbit anything — ← Mova's choice · no support
2. Only the Sun has a partner star, which is too dim for us to see — no support
3. Every star is alone in space — no support
4. Many stars come in pairs or groups orbiting each other — ✓ the right answer · 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 9 · ★ · right ✓

what makes the sun shine, is it like a massive bonfire

1. Yes, it burns coal and wood — no support
2. Yes, it burns oxygen like a candle — no support
3. No, hydrogen is squeezed into helium in its core — ← Mova's choice · ✓ the right answer · score 3
4. No, it reflects the light that comes from other stars — no support

Why: It took the question to ask which statement is true. It chose option 3 with score 3, the only option with support. Its support: lesson 1, line 10: «In the Sun's core, hydrogen nuclei are squeezed together to make helium, and this nuclear fusion releases the energy that makes the Sun shine.», reached through the same lesson line as the sentence the question matched. What matched: the same action «squeeze» (+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 10 · ★ · right ✓

If the Sun were as far away as the next nearest star, what would it look like?

1. Still a huge bright disc, only a bit smaller — no support
2. Just one more star in the night sky — ← Mova's choice · ✓ the right answer · score 11
3. A dark circle with no light — no support
4. A planet with rings — score 9

Why: It took the question to ask a circumstance (with what, when, how). It chose option 2 with score 11, against 9 for the next best. Its support: lesson 1, line 1: «The Sun is a star, the same kind of thing as the tiny dots you see at night, only so close that it fills our day with light.», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+5); the same doer «sun» (+3); the same circumstance (+3). · the question and its options parsed, with trees and pragmatics

Test 11 · ★ · wrong ✗

Aldebaran, Betelgeuse and Altair all have names from which language?

1. Latin — ← Mova's choice · no support
2. Greek — no support
3. Arabic — ✓ the right answer · no support
4. Chinese — 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 1 · formal language · right ✓

Identify the principal process by which energy is generated within the core of the Sun.

1. The reflection of starlight — no support
2. The eruption of volcanoes — no support
3. The fusion of hydrogen nuclei to form helium — ← Mova's choice · ✓ the right answer · score 4
4. The combustion of coal and other fuels in its core — no support

Why: It took the question to ask which statement is true. It chose option 3 with score 4, the only option with support. Its support: lesson 17, line 8: «Deep in the Sun's core, at about 15 million °C, hydrogen nuclei are squeezed together to make helium, releasing enormous energy.», reached through a sentence linked to the one the question matched. What matched: the same action «make» (+2); the same thing acted on «helium» (+2). · the question and its options parsed, with trees and pragmatics

Exam question 2 · formal language · right ✓

Select the response that is consistent with the established facts concerning the colour of stars.

1. It indicates their age, red being youngest — no support
2. It bears no relation to any physical property — no support
3. It indicates their distance, blue being nearest — no support
4. It indicates their temperature, red being coolest and blue-white hottest — ← 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, the only option with support. Its support: lesson 17, line 10: «Star colours show their temperature: red stars are coolest at about 3,000 °C, the Sun is yellow-white at about 5,500 °C, and blue-white stars can be over 20,00…», reached through the remembered sentence the question matched. What matched: the same action «show» (+3); the same thing acted on «temperature» (+3). Against it: a different doer (counts against) (-2). · the question and its options parsed, with trees and pragmatics

Exam question 3 · formal language · wrong ✗

State the principal reason for the twinkling of stars as observed from the surface of the Earth.

1. The intermittent extinction and rekindling of their light — ← Mova's choice · no support
2. The refraction of their light by moving layers of air — ✓ the right answer · no support
3. The passage of birds across their light — no support
4. The rapid rotation of the stars — 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 · wrong ✗

Identify the star which presents the greatest apparent brightness in the night sky.

1. Polaris — ← Mova's choice · no support
2. Sirius — ✓ the right answer · no support
3. Betelgeuse — no support
4. Aldebaran — 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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