Building strong things: bridges, towers and shapes

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

Lesson 86 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 ✗

You build a tower from spaghetti and marshmallows. It keeps leaning over. What will help most?

1. Making the tower much thinner and much taller — ← Mova's choice · score 6
2. Adding diagonal pieces to make triangles — ✓ the right answer · no support
3. Putting all the heaviest pieces at the top — no support
4. Using lots more marshmallows at the very top — no support

Why: It took the question to ask who or what does it. It chose option 1 with score 6, the only option with support. Its support: lesson 68, line 1: «A thunderstorm grows when warm, damp air rises very fast and cools, building a tall, dark tower of cloud called a cumulonimbus, which can reach higher than aer…», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «tall dark tower» (+4); the same action «build» (+2). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 2 · ★★ · wrong ✗

Why do builders of old stone churches use arches over doors and windows?

1. Arches let more rain run off the walls — score 3
2. Stone is strong when stretched, and an arch stretches it — ← Mova's choice · score 6
3. Stone is strong when squashed, and an arch squeezes its stones — ✓ the right answer · score 6
4. Arches use more stone, so they look grander — no support

Why: It took the question to ask why something happens (its cause). 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 86, line 1: «Builders think about two kinds of force inside a structure. Compression squashes a part, like the legs of a table under a heavy load. Tension stretches a part,…», reached through the same lesson line as the sentence the question matched. What matched: the same action «stretch» (+3); the same doer «stone» (+3). The right option, 3, scored 6. · the question and its options parsed, with trees and pragmatics

Test 3 · ★★ · wrong ✗

A plank is laid across a stream and a child stands in the middle. Which is true?

1. The whole plank is only stretched — ← Mova's choice · no support
2. No forces act inside the plank at all — no support
3. The whole plank is only squashed — no support
4. The top of the plank is squashed and the bottom stretched — ✓ 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 4 · ★★ · right ✓

Why does a cardboard box get stronger when you add a corrugated layer, a wavy folded sheet, inside its walls?

1. The wavy folds make the card much stiffer — ← Mova's choice · ✓ the right answer · no support
2. The folds make the card much heavier and softer — no support
3. The folds keep the box dry — no support
4. The folds glue the box shut — 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 5 · ★★ · wrong ✗

A hiker packs a rucksack. To stay steady on a narrow path, where should the heaviest things go?

1. In an outside pocket on one side — no support
2. Low down and close to the back — ✓ the right answer · no support
3. At the very top of the bag — ← Mova's choice · score 6
4. Hanging from a strap below the bag — no support

Why: It took the question to ask where. It chose option 3 with score 6, 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 same lesson line as the sentence the question matched. What matched: it fills the role the question asks for (+3); the same place «top» (+2); 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 · ★★ · right ✓

Engineers want a long, light bridge across a wide river where few supports can stand. Which kind is best?

1. A suspension bridge — ← Mova's choice · ✓ the right answer · no support
2. A beam bridge on many posts — no support
3. A floating bridge of planks — no support
4. A low stone arch bridge — 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 7 · ★★ · right ✓

Why would glass be a poor material for the cables of a suspension bridge?

1. Glass is weak when it is stretched — ← Mova's choice · ✓ the right answer · no support
2. Glass is far too heavy to lift up there — no support
3. Glass rusts quickly in rain — no support
4. Glass is weak when it is squashed — 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 ✓

A table wobbles when pushed sideways. A carpenter adds a slanted brace between a leg and the top. Why does it help?

1. It glues the table to the floor — no support
2. It makes the legs longer — no support
3. It makes a triangle that cannot change shape — ← Mova's choice · ✓ the right answer · score 7
4. It makes the table much heavier, so it cannot move — no support

Why: It took the question to ask why something happens (its cause). It chose option 3 with score 7, the only option with support. Its support: lesson 86, line 2: «The triangle is the strongest simple shape for a frame. Push on the corner of a square frame made of sticks and it folds into a slanted shape, but a triangle c…», reached through the same lesson line as the sentence the question matched. What matched: the same action «change» (+3); the same doer «triangle» (+3); the same thing acted on «shape» (+1). · the question and its options parsed, with trees and pragmatics

Test 9 · ★★ · wrong ✗

Which of these is a structure built mostly from triangles?

1. A round snow igloo — ← Mova's choice · no support
2. A tall brick wall — no support
3. The Eiffel Tower — ✓ the right answer · no support
4. A stone pyramid in Egypt — 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 10 · ★★ · right ✓

why do bridges have all those triangles

1. Triangles look nice, but add no strength — no support
2. Triangles use more steel, so they are heavier — no support
3. Triangles let the wind blow straight through — no support
4. A triangle keeps its shape when pushed, so the frame is rigid — ← Mova's choice · ✓ the right answer · score 2

Why: It took the question to ask which statement is true. It chose option 4 with score 2, the only option with support. Its support: lesson 86, line 2: «The triangle is the strongest simple shape for a frame. Push on the corner of a square frame made of sticks and it folds into a slanted shape, but a triangle c…», reached through the option's own match among the sentences about the question's things. What matched: the same doer «triangle» (+2). · the question and its options parsed, with trees and pragmatics

Test 11 · ★★ · wrong ✗

why's there steel rods inside concrete

1. The steel keeps the concrete warm and stops it cracking in winter — ← Mova's choice · no support
2. The steel stops water soaking into it — no support
3. Concrete is weak in tension, and the steel resists stretching — ✓ the right answer · no support
4. The steel makes the concrete lighter — 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 12 · ★★ · right ✓

Ava says a flat sheet of paper is just as stiff as a rolled one. true?

1. Yes, paper is just as stiff however you shape or fold it — no support
2. No, a flat sheet is stiffer than a rolled one — no support
3. Yes, but only thick paper — no support
4. No, rolling or folding paper makes it much stiffer — ← Mova's choice · ✓ the right answer · score 2

Why: It took the question to ask which statement is true. It chose option 4 with score 2, the only option with support. Its support: lesson 86, line 15: «Folding or rolling a sheet of paper makes it much stiffer.», reached through the same lesson line as the sentence the question matched. What matched: the same action «make» (+3); the same property (+1). Against it: a different doer (counts against) (-1); a different thing acted on (counts against) (-1). · the question and its options parsed, with trees and pragmatics

Test 13 · ★★ · right ✓

my brother reckons tall towers are hardest to tip if heavy stuff's at the top. right?

1. No, weight makes no difference to tipping — no support
2. Yes, heavy stuff at the top pushes the tower down and holds it firm — no support
3. No, a wide base and weight low down make things hard to tip — ← Mova's choice · ✓ the right answer · score 5
4. Yes, but only in strong winds — no support

Why: It took the question to ask which statement is true. It chose option 3 with score 5, the only option with support. Its support: lesson 86, line 5: «Tall things stay up when they are stable: a wide base and most of the weight low down make them hard to tip over. Builders also dig deep foundations, so a tall…», reached through the same lesson line as the sentence the question matched. What matched: the same action «make» (+3); the same thing acted on «things» (+2); the same property (+1). Against it: a different doer (counts against) (-1). · 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 forces designated compression and tension?

1. Both forces squash an object — ← Mova's choice · score 10
2. Compression squashes, whereas tension stretches — ✓ the right answer · score 9
3. Compression stretches, whereas tension squashes — score 7
4. Both forces stretch an object — score 10

Why: It took the question to ask who or what does it. It chose option 1 with score 10, tied with another option at 10 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 85, line 8: «A moving object keeps moving until a force such as friction stops it.», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «object» (+4); it fills the role the question asks for (+4); the same doer «force» (+3). Against it: a different action (counts against) (-1). The right option, 2, scored 9. · the question and its options parsed, with trees and pragmatics

Exam question 2 · formal language · right ✓

Identify the principal reason for which steel bars are placed within reinforced concrete.

1. So that the concrete may dry more quickly — no support
2. So that the concrete may be rendered lighter — no support
3. So that the concrete may conduct electricity — no support
4. So that the concrete may resist stretching as well as squashing — ← Mova's choice · ✓ the right answer · score 5

Why: It took the question to ask which statement is true. It chose option 4 with score 5, the only option with support. Its support: lesson 86, line 10: «Reinforced concrete has steel bars inside it so it can resist stretching as well as squashing.», reached through the remembered sentence the question matched. What matched: the same action «resist» (+4); the same doer «concrete» (+1). · the question and its options parsed, with trees and pragmatics

Exam question 3 · formal language · right ✓

It is given that a square frame is readily pushed out of shape. Determine the addition by which it may be rendered rigid.

1. A heavier weight placed upon its top — no support
2. A second square frame placed beside it and joined to it — no support
3. A diagonal strut dividing it into two triangles — ← Mova's choice · ✓ the right answer · score 3
4. A coat of paint upon each side — 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 86, line 12: «Adding a diagonal strut to a square frame divides it into two triangles and makes it rigid.», reached through the option's own match among the sentences about the question's things. What matched: the same action «divide» (+3); the same place «two triangles» (+2). Against it: a different doer (counts against) (-1); a different thing acted on (counts against) (-1). · the question and its options parsed, with trees and pragmatics

Exam question 4 · formal language · wrong ✗

Select the response that is consistent with the established facts concerning the stability of an object.

1. An object with a narrow base and its weight high up is hardest to tip — ← Mova's choice · no support
2. The shape of the base has no effect upon stability — no support
3. Only heavy objects can be stable — no support
4. An object with a wide base and its weight low down is hard to tip over — ✓ 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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