How we know: measuring the sky

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

Lesson 28 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 · ★★★ · wrong ✗

Lily thinks astronomers must fly to stars to know what they're made of. What is right?

1. She is right, probes have visited all of them and dug up samples — no support
2. The lines in their light show what they are made of — ✓ the right answer · no support
3. They guess from the star's colour only, nothing else helps — ← Mova's choice · score 7
4. Nobody knows what stars are made of, it is still a total mystery — no support

Why: It took the question to ask which statement is true. It chose option 3 with score 7, the only option with support. Its support: lesson 24, line 17: «Galaxies spin so fast that their visible stars and gas cannot hold them together, so astronomers think they contain invisible dark matter, about five times as…», reached through the option's own match among the sentences about the question's things. What matched: the same doer «astronomers» (+4); the same action «think» (+3). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 2 · ★★★ · wrong ✗

Hold a pencil close to your face, then far, and wink each eye. When does it jump less?

1. It never jumps at all — ← Mova's choice · no support
2. It jumps the same both times — no support
3. When it is far away, just like distant stars — ✓ the right answer · no support
4. When it is close — 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 ✓

Why would it be easier to measure parallax from a planet with a much bigger orbit than Earth?

1. Looking from two places farther apart makes the shift bigger — ← Mova's choice · ✓ the right answer · no support
2. Stars are closer to the bigger orbits, so they look larger — no support
3. Stars stand still for bigger planets, so they are easier to aim at — no support
4. The air is much clearer for planets with big orbits — 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 ✓

An ambulance's siren drops in pitch as it drives away. Which sky clue works like that?

1. Parallax of a nearby star — no support
2. The phases of Venus — no support
3. Redshift of a galaxy moving away — ← Mova's choice · ✓ the right answer · score 2
4. Dark lines of helium — no support

Why: It took the question to ask what it is done to. It chose option 3 with score 2, the only option with support. Its support: lesson 28, line 4: «Light from a galaxy rushing away is stretched towards red, like a siren dropping its pitch as an ambulance drives off: the bigger the stretch, the faster it go…», reached through the same lesson line as the sentence the question matched. What matched: the same doer «galaxy» (+3); the same property (+1). Against it: a different action (counts against) (-2). · the question and its options parsed, with trees and pragmatics

Test 5 · ★★★ · wrong ✗

Why was it so amazing that helium was found in the Sun before on Earth?

1. Scientists identified a new element from 150 million km away — ✓ the right answer · no support
2. It proved that the Sun is really cold underneath its glowing outside — no support
3. The Sun is made only of helium — ← Mova's choice · score 4
4. Helium is the heaviest element — no support

Why: It took the question to ask why something happens (its cause). 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 the option's own match among the sentences about the question's things. What matched: the same action «make» (+2); the same circumstance (+2). The right option, 1, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 6 · ★★★ · wrong ✗

Two Cepheids pulse equally slowly, but one looks much dimmer. What can you conclude?

1. They must be the same distance — ← Mova's choice · score 2
2. The dimmer one is younger — no support
3. The dimmer one is much farther away — ✓ the right answer · no support
4. The dimmer one is much nearer — no support

Why: It took the question to ask what it is done to. It chose option 1 with score 2, the only option with support. Its support: lesson 28, line 14: «Henrietta Leavitt found in 1912 that certain pulsing stars called Cepheids pulse more slowly the brighter they really are, letting astronomers measure great di…», reached through the same lesson line as the sentence the question matched. What matched: it fills the role the question asks for (+2); the same thing acted on «great distances» (+1). Against it: a different doer (counts against) (-1). The right option, 3, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 7 · ★★★ · right ✓

Payne's result was first refused by other astronomers. What does her story show about science?

1. Good evidence can win even when experts disagree at first — ← Mova's choice · ✓ the right answer · no support
2. Young scientists are always wrong — no support
3. Once rejected, an idea is never accepted — no support
4. Whatever famous experts say is always right in the end, every time — 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 ✗

Uranus kept drifting off its predicted path. What did Le Verrier reason?

1. The telescopes must all be broken and showing it wrong — score 3
2. An unseen planet's gravity must be pulling it — ✓ the right answer · no support
3. Uranus must be running out of fuel and slowing down — no support
4. Uranus must be changing its mass as it loses its rings — ← Mova's choice · score 6

Why: It took the question to ask what it is done to. It chose option 4 with score 6, against 3 for the next best. Its support: lesson 14, line 11: «Uranus has 13 narrow dark rings and more than 25 known moons.», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+4); the same thing acted on «13 narrow dark rings» (+2). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 9 · ★★★ · wrong ✗

If Earth went round the Sun faster at the same distance, what would that tell us about the Sun?

1. It would be lighter than we think — score 3
2. It would be colder — no support
3. Nothing at all — ← Mova's choice · score 10
4. It would be heavier than we think — ✓ the right answer · no support

Why: It took the question to ask what it is done to. It chose option 3 with score 10, against 3 for the next best. Its support: lesson 5, line 9: «The Earth spins once in about 24 hours, giving day and night, and goes round the Sun in about 365.25 days.», reached through the remembered sentence the question matched. What matched: the same doer «earth» (+5); the same place «sun» (+3); the same light verb (be, have, do, get, go) (+2). The right option, 4, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 10 · ★★★ · right ✓

Eratosthenes saw no shadow at noon in one city but a shadow at another the same day. Why?

1. The other city was much nearer the Moon, which blocked the sunlight — no support
2. Earth's surface is curved, so the Sun hits at different angles — ← Mova's choice · ✓ the right answer · score 5
3. The Sun was in two places at once — no support
4. One city had taller buildings — no support

Why: It took the question to ask why something happens (its cause). It chose option 2 with score 5, the only option with support. Its support: lesson 28, line 9: «Around 240 BC Eratosthenes in Egypt estimated the size of Earth by comparing the shadows of the Sun at two cities: because Earth's surface is curved, the noon…», reached through the same lesson line as the sentence the question matched. What matched: the same thing acted on «surface» (+3); the same action «curve» (+2). · the question and its options parsed, with trees and pragmatics

Test 11 · ★★★ · wrong ✗

bro reckons nobody can know how far stars are, it's all made up. true?

1. Yes, star distances are pure guesses — ← Mova's choice · no support
2. Yes, nobody has ever tried — no support
3. No, parallax measures nearby stars directly, like Gaia did — ✓ the right answer · no support
4. No, astronauts have measured every one of them with long lasers — 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 · wrong ✗

Which of the following statements most accurately characterises the method of stellar parallax?

1. The pulsation of certain variable stars — ← Mova's choice · no support
2. The apparent shift of a nearby star as the Earth orbits the Sun — ✓ the right answer · no support
3. The stretching of light from galaxies which are receding from the Earth — no support
4. The variation in colour of a star with its temperature — 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 ✓

Identify the element first discovered in the spectrum of the Sun in 1868.

1. Helium — ← Mova's choice · ✓ the right answer · no support
2. Iron — no support
3. Hydrogen — no support
4. Oxygen — 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 ✗

Ascertain the means by which the planet Neptune was located in 1846.

1. Observation by a passing spacecraft — ← Mova's choice · no support
2. Detection of its radio emissions — no support
3. Prediction from the disturbed motion of Uranus — ✓ the right answer · no support
4. Chance observation with the naked eye — 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 · right ✓

Select the response that is consistent with the established facts concerning the composition of stars as shown by Cecilia Payne in 1925.

1. Stars consist mostly of hydrogen and helium — ← Mova's choice · ✓ the right answer · no support
2. Stars consist mostly of iron and nickel — no support
3. Stars have the same composition as the Earth — no support
4. Stars consist mostly of carbon and oxygen — 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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