Topic 13 Light: sources, straight lines, shadows — what needs James (0)
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Question types (8)
One exemplar per question type in the test bank; approving a type approves every item written to it. The full type sheet.
Topic 13 · Light: sources, straight lines, shadows · Type 1 · bank item PP-1 · tests ENE3-010
EasyMCQType 1 — a night scene is described (what is on, what is bright); which thing is the light source · PP-1
At night, a streetlight is on, and under it a parked car, a mailbox and a tree are all bright. Which thing is the light source?
- a) the parked car
- b) the mailbox
- c) the streetlight ← key
- d) the tree
Why it is this type: The streetlight makes light. / The light lands on the car, the mailbox and the tree, and they are lit up. / A light source makes light, so the streetlight is the light source.
Recommendation: Approve as the exemplar
More from the sheet on this type
(The scene is described — what is on, what is bright — so the student infers the source; the stem no longer says the streetlight "lights up" the others.)
Topic 13 · Light: sources, straight lines, shadows · Type 1 · bank item PP-2 · tests ENE3-010
EasyMCQType 1, second case — a night scene is described (what is on, what is bright); which thing is the light source · PP-2
At night, the Moon is bright in the sky, and a streetlight is on above a parked car and a mailbox. Which thing is the light source?
- a) the Moon
- b) the parked car
- c) the mailbox
- d) the streetlight ← key
Why it is this type: The streetlight makes light. / Sunlight lands on the Moon, and the Moon is lit up; the Moon does not make light. / The car and the mailbox are lit up too, so the streetlight is the light source.
Recommendation: Approve as the exemplar
Topic 13 · Light: sources, straight lines, shadows · Type 2 · bank item PP-3 · tests ENE3-011
EasyMCQType 2 — which of four drawings shows how light travels from a flashlight to a wall
Four drawings show light leaving a flashlight and reaching a wall. Which drawing shows how the light travels?
- a) drawing J ← key
- b) drawing K
- c) drawing L
- d) drawing M
Why it is this type: Light travels in straight lines. / Drawing J shows straight lines from the flashlight to the wall. / Drawings K, L and M show zigzag, looping and curved paths, and light does not travel like that.
Recommendation: Approve as the exemplar
Topic 13 · Light: sources, straight lines, shadows · Type 4 · bank item PP-4 · tests ENE3-011 ENE3-012
MediumMCQType 4 — a shadow's place is described; why is the shadow there
A flashlight is to the right of a toy car on the floor, and the car's shadow is on the floor to its left. Why is the shadow there?
- a) The flashlight pushes the car's shadow out behind it.
- b) The shadow comes out of the car and lands on the floor.
- c) The car's dark side shows on the floor behind it.
- d) The car blocks the light from reaching the floor behind it. ← key
Why it is this type: Medium because: the reason rests on two ideas (straight lines; blocking) applied to a fresh scene, against three catalogued beliefs about shadows. Every option is one statement of the same shape.
The why line (what a student reads after answering): Light travels in straight lines from the flashlight. / The car blocks some of the light, and light cannot bend around it. / No light reaches the floor behind the car, so that dark place is the shadow.
Recommendation: Approve as the exemplar
Topic 13 · Light: sources, straight lines, shadows · Type 5 · bank item PP-5 · tests ENE3-017
MediumMCQType 5 — a child in a place with no light at all, for a stated time: what does she see
Nadira sits in a cellar with the door shut and no light at all for ten minutes. What does she see?
- a) the walls, faintly
- b) nothing ← key
- c) the walls, clearly
- d) only the door
Why it is this type: Medium because: the register's trap ("eyes adjust") sits in option a, and the stated ten minutes invites it; the student applies the rule against the pull of the trap.
The why line (what a student reads after answering): The cellar has no light at all. / No light comes from the walls or the door to Nadira's eyes. / You see something only when light from it reaches your eye, so she sees nothing, however long she waits.
Recommendation: Approve as the exemplar
Topic 13 · Light: sources, straight lines, shadows · Type 6 · bank item PP-6 · tests ENE3-012
HardMCQType 6 — a lamp is to one side of an object; then the lamp is moved to the other side; on which side is the shadow now
MCQ (converted 29 Sep 2026)
A lamp is to the right of a bottle on a table. Then the lamp is moved to the other side of the bottle. On which side of the bottle is the shadow now?
- a) on the left side
- b) on the right side (key B)
- c) under the bottle
- d) on both sides
Why it is this type: The lamp was to the right of the bottle, so the shadow was on the left. / Now the lamp is to the left of the bottle. / The bottle blocks some of the light, and the shadow is on the side away from the lamp: the right side.
Recommendation: Approve as the exemplar
More from the sheet on this type
fb: The shadow was on the left while the lamp was on the right; the lamp has moved, so the shadow has moved too. · The lamp is now on the left, and the shadow is on the side away from the lamp: the right. · Under the bottle is where the bottle stands; the shadow falls on the table beside it, away from the lamp. · One lamp makes one shadow, on the side away from the lamp.
Was typed ("right"); James's typed-item ruling (29 Sep 2026; vault 10 Rules/A typed answer is asked only where the question is closed, and every correct answer is accepted.md) — a direction is an open question ("towards the table's edge", "away from the lamp", "the other side" are all true), and James named direction as the case for up / down / left / right options. Still hard: two steps — place the lamp after the move, then place the shadow away from it — and the chain is what splits left from right; the two other options are the beliefs that a shadow sits under its object or on every side. The stem prints "right" only as the lamp's OLD place, which is the given, not the answer.
Topic 13 · Light: sources, straight lines, shadows · Type 7 · bank item PP-7 · tests ENE3-010 ENE3-017
HardMCQType 7 — in a shed with no light, a flashlight is pointed at a shelf and he sees it: just before the light reaches his eyes, which thing does it come from
MCQ (converted 29 Sep 2026)
Soren is in a shed with no light at all. He turns on a flashlight, points it at a shelf, and now he sees the shelf. Just before the light reaches his eyes, which thing does it come from?
- a) the shelf (key A)
- b) the flashlight
- c) Soren's eyes
- d) the Sun outside the shed
Why it is this type: The flashlight is the light source, so it makes light. / The light lands on the shelf. / Then light comes from the shelf to Soren's eyes, and you see something only when light from it reaches your eye.
Recommendation: Approve as the exemplar
More from the sheet on this type
fb: The flashlight's light lands on the shelf, and light from the shelf reaches his eyes, so he sees the shelf. · The flashlight makes the light, but he is looking at the shelf: the light he sees by comes from the shelf, after it landed there. · Eyes make no light; light comes to them. · The shed has no light at all from outside; the flashlight is the only light source here.
Was typed ("the shelf"); James's typed-item ruling (29 Sep 2026; vault 10 Rules/A typed answer is asked only where the question is closed, and every correct answer is accepted.md) — a described thing is an open key (the shelf, the shelf's light, the wood, what he is looking at …). Still hard: two atoms chained — the flashlight makes the light and it lands on the shelf (010); seeing the shelf needs light FROM THE SHELF reaching the eye (017). Most students pick the flashlight; the key needs the second step. The four options are the things the scene names plus the eye-beam belief and the absent Sun, so nothing is the key by elimination. The stem's four sentences are within the hard tag (S23).
Topic 13 · Light: sources, straight lines, shadows · Type 8 · tests ENE3-010
ProposedHardProposed: Type 8 — a night scene names four things, one of them the Moon; type the name of the thing that is the light source
text entry
On a night walk a girl sees four things: a lit candle in a window, the full Moon, a white wall and a mirror. Only one of them is a light source. Type its name.
Accepted answers (typed): one of four things the stem names): candle · the candle · a candle · the lit candle · lit candle · candel · the candel · the candle in the window · candle flame · the candle flame · the candle's flame · flame · the flame
Why it is this type: Hard because: the student refuses the Moon (the register's LGT-06 trap), the bright wall and the mirror — three things that are bright without making light — and produces the one name; type 1 asks the same sort at four options, so this is its typed, harder form. The girl needs a fresh name from the register (build_tools_names.py) before use.
The why line (what a student reads after answering): A light source makes light. / The candle's flame makes light. / The Moon, the wall and the mirror are bright only because light lands on them and bounces off. / So the candle is the light source.
Recommendation: Approve the proposed type
More from the sheet on this type
The sheet lost both typed hard types today, and James's 28 Sep ruling still wants the hard end typed where a closed key exists. This topic coins two terms ("light source", "shadow") that PR-10 and PR-11 already ask by recall; a closed typed key that is not a definition is one of a SET THE STEM NAMES.
The lessons (4)
Each lesson in teaching order: its one-line summary, the article, the script and the quiz, then your ruling.
Topic 13 · Lesson 1
Lesson 1 Light comes from a light source
a lamp lights a book; a flashlight, the Sun, a candle; then the bright page that does not make light, and the Moon.
Topic 13 · Lesson 2
Lesson 2 Light travels in straight lines
a beam in the dust, a sun stripe through a gap, a lamp seen down a straight tube and lost in a bent one.
Topic 13 · Lesson 3
Lesson 3 Where will the shadow be?
the hand in front of the flashlight; the same ball with the light on the left, the right, above; take the ball away and the shadow goes. The shadow's edges in every drawing are computed from the lines that graze the object.
Skill: write-like-james @ 8b55b65 · built 6 October 2026 by build_tools_needs_you.py