Skill: write-like-james @ b0fa825 · the build: write-lesson, write-mcqs, write-video-script, review-lesson (two blind reads and a re-read), review-figures, review-accuracy @ b0fa825
Topic 15 "Why the mass stays the same" — your read (2 October 2026)
Skim first
The lessons in teaching order, each with its one rule sentence; then the intro script; then the question types. The review page follows.
The lessons and their rules
| Lesson | Atom | Rule sentence |
|---|---|---|
| L01 Break it into pieces: the mass stays the same | MAT4-040 | Break a thing into pieces: the mass stays the same. No stuff was added, no stuff was taken away. |
| L02 Add the pieces to find the whole | MAT4-041 | Mass of the whole = mass of the pieces added together. The whole and its pieces balance. |
| L03 Mix it: the mass stays the same | MAT4-042 | Mass of the mixture = masses of the parts added together. Each material is still itself, so the mass stays the same. |
The intro script (115 words, about 58 s)
Here's Miss Vance's class on a hike, stopping for a snack. Finley opens his backpack, and his bag of tortilla chips is all crumbs. 'There's less of it now,' he says. Fiona shakes drink powder into her bottle of water and stirs. Soon she cannot see the powder. 'That's gone too,' says Finley. But is there really less chip in the bag, and did the powder go anywhere at all? Back at school, a digital scale can settle it. To find out, we will look at what happens to the mass when a thing breaks into pieces, and when two things are mixed together. Okay, so are you ready to put it on the scale?
The question types (from TYPES_G4T15.md)
- Type 1: Predict the reading after a thing is broken into pieces, every piece on the pan; the whole's reading drawn or stated; four numbers (half, a little less, the same, a little more).
- Type 2: Pick the true sentence about the pieces' reading, including the boundary where some stuff left the pan.
- Type 3: Why the reading stays the same: four reasons, one the rule's reason.
- Type 4: Which case keeps the mass (or loses it): four cases, one with every piece back on the pan.
- Type 5: A claim fixed as wrong (or right) in the stem — or a reading that breaks the pattern: which sentence shows it.
- Type 6: Add the pieces to find the whole (or run it backwards): four numbers, or four lines of working.
- Type 7: Pan-balance prediction: a whole against the pieces of a second one; four outcomes.
- Type 8: Type the mass of the whole from two drawn readings, three stated masses, a level balance, or the whole take away one piece.
- Type 9: Predict the mixture's reading or how it compares: four numbers or four comparisons.
- Type 10: Type the mass of the mixture from two drawn readings or two stated masses, with the containers tracked back onto the pan, or the mixture take away one part.
Three lessons: break a thing into pieces and the scale reads the same number, because no stuff was added and no stuff was taken away; add the pieces' masses and you get the whole's mass back, so the whole and its pieces balance; mix two things, or stir sugar into water, and the mass of the mixture is the two masses added together. Every key agreed by two cold readers, then by a third on the rebuilt bundle; the figure review and the guidance-and-accuracy review are applied, and the re-read's three polish notes too. Pictures are placeholders until you answer.
The questions the author put to you (built as recommended)
1. Does the sugar-in-water case belong here, while Topic 14 teaches "dissolved is not gone"?
L03 stirs 20 grams of sugar into 250 grams of water; the sugar goes out of sight and the scale reads 270 grams. The reason the mass holds is Topic 14's own sentence, recalled word for word: "A dissolved material is not gone. It is still there, in the liquid." The scale reading is the proof of that sentence.
Built: kept, with Topic 14's sentence under the sugar case and "disappears" cut from the intro.
Recommendation: keep.
Keep / cut the sugar case and its two dissolving items
2. May the bank run the rule backwards, a whole minus one piece, as medium and hard items?
L02 teaches adding the pieces to get the whole. Six bank items and one practice item give the whole and one piece and ask for the other piece, so the child subtracts. Two-digit subtraction is grade 2 maths, and every why shows the subtraction line.
Built: kept; the MCQ forms tagged medium, the typed forms tagged hard.
Recommendation: keep.
Keep / retag all to hard / cut
3. On the drawn display, "45 g" or "45 grams"?
The Grade 3 scale card printed "150 g" and taught "read the number and the g". Every drawn display here prints the symbol, as a real scale does. Every sentence a child reads or hears says "grams".
Built: "g" on the drawn display, "grams" in every sentence.
Recommendation: keep.
Keep / words on the display too
4. Should PP-8's "lighter" distractor be a false mechanism, or the reviewer's compensation line?
PP-8 asks why a pizza cut into eight slices still reads 400 grams. The reviewer proposed "The slices are lighter, but there are more of them." A careful nine-year-old can defend that line (each slice lighter, more slices, the same total), so it would be a second right answer. The fixer wrote "The slices are lighter, but the scale adds a gram for each slice." instead, a mechanism that is plainly false.
Built: the false mechanism.
Recommendation: keep the false mechanism.
Keep / use the reviewer's line
The lessons
5. L01 Break it into pieces: the mass stays the same — Frances says the four pieces of the chocolate bar are lighter than the whole bar; the scale reads 45 grams before and after. A cracker crumbled to crumbs reads 8 grams both times, a ball of clay pulled into five little balls reads 60 grams both times; one crumb on the floor, and the scale reads a little less. page
6. L02 Add the pieces to find the whole — Finley's three clay pieces read 25, 20 and 15 grams; can you say the number before the scale does? 25 + 20 + 15 = 60. Then the whole second bar against the first bar's two pieces on the pan balance: 45 against 30 + 15, and the pans hang level. page
7. L03 Mix it: the mass stays the same — the class makes bean-bag filling: a cup of rice (180 grams) and a cup of beans (200 grams) mixed read 380 grams, though Finley said "mixed together there is more". Then sugar (20 grams) stirred into water (250 grams) reads 270 grams, though the sugar is out of sight. page
Applied without asking
The L01 video now says what the article already said, that a crumb on the floor makes the scale read a little less (two quiz items test it); the "three pieces" card drew five balls and now draws three; the sugar and the salt on the drawn cards were invisible against the cup, so a full cup looked like an empty one, and both now show grain dots while every empty cup is shaded; a jar that "read 0 grams" needed a zeroing the course never taught, so the jar now has a mass of 100 grams; a stapler item's hidden text gave its reading away and now says only "a number and the letter g"; the mixed cup is heaped above its rim so the picture never says "mixing makes less"; one sentence says that each cup's reading is the cup with what is in it; Topic 14's two sentences are recalled word for word ("material", not "part"), and "disappears" is cut; nine bank items that were lesson scenes with the nouns changed are re-scened with a different move, one twin is cut, and the clone pairs are marked never to be drawn together; from the re-read, the four pan-balance items drop their "hangs lower at first, then…" option for a belief a child holds (the pan with more pieces, or with the bigger piece, hangs lower), the dissolving item stirs protein powder instead of lemonade powder, and the flatbread item says its third piece stays on the plate. 52 items, 16 to 18 per atom; summary before practice; five photo and four cartoon placeholders with briefs.
Also on the site
Topic intro and poll · summary and three questions · mixed practice · the PP100 bank · the type sheet
After you answer
Nothing on the page changes if you keep all four; the reviewer's PP-8 line, or words on the display, is a short text pass. Either way the picture pass starts, and the five-video batch goes with Grade 4's first batch on your word.
Build record (the structural decisions, the counts, v2 and v3)
Skill: course-build → write-lesson, write-video-script (intro, three lesson scripts, summary), write-mcqs (attached questions, quizzes, mixed practice, PP100 bank and type sheet), design-check-sequence, write-example-sequence, sentence-atomise, write-explanation @ b0fa825
Grade 4 Topic 15 — Why the mass stays the same — build record (v1, 2 October 2026)
What this is, in plain words
Three short lessons that show a child the same thing three ways: break a chocolate bar, a cracker or a ball of clay into pieces and the scale reads the same number; add the pieces' masses and you get the whole's mass back, so the whole and its pieces balance; mix rice and beans, or stir sugar into water, and the mass of the mixture is the two masses added together. The reason is said in the child's own words every time — the pieces (or the parts) are the same stuff; no stuff was added, and no stuff was taken away — and the one honest boundary is said once (a crumb on the floor is stuff off the pan, so the scale reads a little less). Three beliefs are confronted by name: the pieces are lighter (the crumbled cracker), mixing makes more, and dissolving makes it lighter. No new word is coined: mass and grams are Grade 3's, mixture is Topic 14's.
Files: content/G4T15.py (topic, intro, summary, practice) · content/G4T15_lessons.py (L01–L03) · content/G4T15_pp100_bank.py (53 items) · content/figures.py (48 figures) · records/TYPES_G4T15.md · blind/2026-10-02/ (the blind bundle and its sequestered keys) · handoff/G4T15/videos/batch_G4T15.json + READY.md (built, brief-checked, NOT sent).
Structural decisions (in place of a blueprint)
Running scene. Miss Vance's class at a table with a digital scale: a chocolate bar, a cracker and a ball of clay broken up (L01); Finley's three clay pieces put back together, then a second bar against the first bar's pieces on the pan balance (L02); the class making bean-bag filling — a cup of rice and a cup of beans mixed, then sugar stirred into water (L03). Characters: Miss Vance; Finley, Fiona, Frances (grade4/NAMES_POOL.md, Topic 15 row); the three names also carry every claim in the quizzes and the practice; bank claim-makers are unnamed. The intro is the same class on a hike (crushed tortilla chips, drink powder in a water bottle), so it never names L01's example.
Lesson order and titles. L01 Break it into pieces: the mass stays the same (MAT4-040) → L02 Add the pieces to find the whole (MAT4-041) → L03 Mix it: the mass stays the same (MAT4-042, capstone). The atoms' own order: the fact first, the routine that uses the fact second, the transformation that reuses both last. Titles name the skill in student words; "the mass stays the same" is the plain phrase throughout, never "is conserved".
Headache scenes. L01: Frances says the four pieces are lighter than the whole bar; what will the scale read? L02: Miss Vance asks what the scale will read with all three clay pieces on it — can you say the number first? L03: Finley says mixed together there is more; what will the scale read? Each question comes from a person who would ask it; no invented sign or game.
Example sequences, written out.
- L01 (a fact true of every case — the universal-attribute form; no minimal-difference non-example exists for "breaking keeps the mass", so examples only, the rule last): frame "The whole X: N grams. The pieces: N grams. The mass is the same." E the bar snapped into four, 45 grams → E the cracker crumbled into crumbs, 8 grams (the crumbled-cracker belief) → E the ball of clay pulled into five little balls and spread out, 60 grams → the boundary said in words (a crumb on the floor: stuff off the pan, the scale reads a little less) → rule. The reason sits inside every frame: the pieces are the same stuff, just broken up; no stuff was added, and no stuff was taken away.
- L02 (a routine; the maths mirror is adding two-digit masses, grade 2): worked on the clay (25 + 20 + 15 = 60, L01's 60-gram ball — one dataset per scene), the word equation "mass of the whole = mass of the pieces added together" on a card, the calculation on its own line; shown again on the bar's two pieces (30 + 15 = 45); then the pan balance — the whole second bar against the two pieces — predicted from the two sums (45 and 45) and shown level. Grade 3 Topic 18's two balance sentences are recalled word for word first.
- L03 (a transformation; NGSS 5-PS1-2's mixing clause only): frame "Two cups, not mixed: N grams. Mixed together: N grams. The mass is the same." E rice and beans, 180 + 200 = 380 grams (Finley's "mixed together there is more") → E sugar stirred into water, 250 + 20 = 270 grams (the sugar dissolves; Frances's "the sugar is gone, so it is lighter") → rule. The reason is Topic 14's line recalled: each part of a mixture is still itself, so no stuff was added and no stuff was taken away. The setup is said in words: a cup's reading is the cup with what is in it, and every cup that was on the pan before the mix goes back on the pan after it — so no equation labels a quantity the pan did not hold.
Check types. L01 type (a) fluency (one Grade 3 recall first); L02 type (b) scaffolded → bare (one Grade 3 recall first); L03 type (c) what / why / misconception / transfer with the numeric predictions last (one Topic 14 recall first). Records below.
Video calls. All three lessons video and article: the display counting up and stopping, the "?" becoming the number, and the beam settling level are motion the article cannot show; L01's three before-and-after cards are the lesson. None could do without a video.
Coined terms. None. terms={}, coined_at={}; S33 / S34 have nothing to check. The hard tier of the bank therefore recalls no term; its typed items are produced numbers.
Figures. 48: 36 svg (the register's digital scale imported from Grade 3 Topic 17, the pan balance from Topic 18, before-and-after cards, three-scale strips, word-equation cards, rule cards, item scales) · 5 photo placeholders (the bar, the cracker, the clay, the rice and beans, the sugar and water) · 4 cartoon placeholders (the class at the table, Fiona snapping, Finley pulling, Frances pouring); IMAGE_KINDS and IMAGE_BRIEFS complete (asserted). On-screen the display prints "45 g" as a real scale does; prose says "45 grams" (the on-screen unit is James's open call — the symbol was used on displays only).
Questions for James
1. Does the sugar-in-water case (dissolving) belong in this topic, when Topic 14 is teaching "dissolved is not gone" in parallel?
Context: the brief names "dissolving makes it lighter" as a belief this topic confronts; MAT4-042's prerequisite is MAT4-020 (mixture) only. L03 states the fact in one line ("The sugar is still in the water. You cannot see it, but it is there.") and never teaches dissolving.
Recommendation: keep it, as built — the mass is the evidence that the sugar is still there, which is exactly what Topic 14 asserts.
Choices: keep / cut the sugar case and the two dissolving items, leaving the belief to Topic 14.
2. May the bank run the rule backwards — a whole minus one piece, a mixture minus one part — as medium and hard items?
Context: the atom's maths mirror is adding two-digit masses; the reverse is two-digit subtraction, also grade 2. Four bank items and one practice item do it (PP-27, PP-28, PP-36, PP-42, PP-50, PR-7), each with the subtraction line in its why.
Recommendation: keep them (they are the same word equation read the other way), tagged medium (MCQ) and hard (typed).
Choices: keep / retag all to hard / cut.
3. On the drawn display, "45 g" or "45 grams"?
Context: the Grade 3 register's scale prints "150 g" and Grade 3 taught "read the number and the g"; S29 counts the symbol in four alt texts and one on-screen cue.
Recommendation: keep "g" on the drawn display (the thing a real scale shows) and the word everywhere a sentence is read or spoken, as built.
Counts
- Lessons 3 · quiz items 9 + 10 + 11 = 30 · attached 3 + summary 3 · practice 12 (3 Grade 3 retrievals) · bank 53.
- Word counts (
grade4/check_g4_articles.py): articles L01 295 · L02 299 · L03 286 (its count; with captions 391 / 409 / 412); scripts 148 · 149 · 149; intro 114 (two question marks, the ready line included); summary 96 with the opener. 0 FAIL. - Bank: 18 easy · 19 medium · 16 hard; per atom MAT4-040 17 (9 / 6 / 2) · MAT4-041 18 (5 / 7 / 6) · MAT4-042 18 (4 / 6 / 8); 11 typed numeric (all hard) + 5 hard MCQs; MCQ key positions 5 / 12 / 13 / 12; ten types (sheet:
records/TYPES_G4T15.md).
What each lesson teaches
| Lesson | Atom | Rule (lexicon, word for word) | Check type | Items |
|---|---|---|---|---|
| L01 Break it into pieces: the mass stays the same | MAT4-040 | When you break a thing into pieces, the mass stays the same. No stuff was added, and no stuff was taken away. | (a) fluency | recall (G3 T17) · 5 what-does-it-read · 2 claims (n, y) · 1 why |
| L02 Add the pieces to find the whole | MAT4-041 | To find the mass of the whole, add the masses of the pieces together. The whole and its pieces balance, because their masses are the same. | (b) scaffolded → bare | recall (G3 T18) · 3 scaffold numeric · 3 bare numeric · 2 balance MCQ · 1 claim (y) |
| L03 Mix it: the mass stays the same | MAT4-042 | When things are mixed together, the mass of the mixture is the masses of the parts added together. Each part is still itself, so the mass stays the same. | (c) what / why / misconception / transfer | recall (T14) · what · why FRQ · 4 claims (n n y y) · transfer MCQ · 3 numeric |
design-check-sequence records
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Skill: design-check-sequence @ b0fa825
Part: L01 (one part)
Type: (a) — the student places a case under one rule (every piece on the pan → the same; some stuff off the pan → less); one step, two or three labels.
Plan: 9 items. q1 Grade 3 recall (what a digital scale measures; 3 opt). q2–q6 what-does-it-read, options less / N grams / more (3 opt), five fresh things: a cookie crumbled (figure), a stick of chalk snapped (figure), carrot slices with one on the floor (figure; the boundary), paper torn into strips, a mint candy crushed with powder on the fingers (the boundary again). q7 Frances's crumbs-are-lighter claim (no); q8 Finley's snapped-pencil claim (yes). q9 the reason, three reasons as options. Three-option key string 0 1 1 0 1 0 0; two-option n y. Stems one or two sentences plus the ask; the ask is the same sentence across the run.
Belongs in practice/test instead: the four-option bank forms (type 1, type 2) and the fixed-wrong-claim form (type 5).
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Skill: design-check-sequence @ b0fa825
Part: L02 (one part)
Type: (b) — read each piece, add, predict; the student can be right at the reading and wrong at the sum.
Plan: 10 items. q1 Grade 3 recall (level pans mean the same mass; 3 opt). Worked example on the page (the clay, 25 + 20 + 15). Scaffold on a SECOND case, a pretzel rod in two pieces drawn on two scales: q2 read piece 1 (numeric, 12), q3 read piece 2 (numeric, 9), q4 add to predict the whole (numeric, 21). Bare on THIRD cases: q5 a granola bar's two drawn pieces (numeric, 44), q6 a bagel with masses stated (numeric, 75), q7 a candle in three (numeric, 50). Then the balance predictions: q8 a whole roll against pieces of the same mass (level), q9 a flatbread against two pieces whose sum is less (the whole hangs lower). q10 Frances's two-pieces-balance-the-whole claim (yes). Every numeric stem says "grams" and "Type the number". Three-option key string 0 2 1; two-option y.
Belongs in practice/test instead: the reverse (whole take away one piece) and the chained pie item (bank types 6 and 8).
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Skill: design-check-sequence @ b0fa825
Part: L03 (one part)
Type: (c) — the payoff is a because-clause (each part is still itself, so the mass is the parts added together) and the register names two beliefs.
Plan: 11 items. q1 Topic 14 recall (things mixed together are a mixture; 3 opt). q2 the what (beads poured into buttons: less / the same / more). q3 the why as a written answer on a FRESH case (oats and nuts; starter "Each part of the mixture…") — read against the article's rice-and-beans and sugar-and-water cases and every quiz case. q4 Fiona's mixing-makes-more claim (gravel into soil; no); q5 Frances's dissolved-so-lighter claim (drink mix; no); q6 Finley's cocoa-and-milk claim (yes); q7 Fiona's peas-and-corn claim (yes). q8 transfer sentence (honey in tea). q9–q11 numeric predictions last: sand and pebbles (drawn, 235), two kinds of pasta (stated, 195), water and salt (drawn, 240). Three-option key string 0 1 2; two-option n n y y.
Belongs in practice/test instead: the four-option fixed-wrong-claim form and the reverse mixture items (bank types 5, 9, 10).
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The key strings
- Attached questions, video order (L01, L02, L03, S1, S2, S3): B C B C B A — the batch tool's string; B 3 of 6 (50 %).
- L01 three-option 0 1 1 0 1 0 0 · two-option n y. L02 three-option 0 2 1 · two-option y. L03 three-option 0 1 2 · two-option n n y y.
- Practice: MCQ keys 0 0 1 1 2 0 1 1 (three-option items 0 0 1 1 2 1; two-option n n); three numeric, one FRQ.
- Bank MCQ positions 5 / 12 / 13 / 12 (42 MCQs); S7 clean.
The misconception rows, and what was done
The vault's elementary physics catalogue is silent on matter conservation; the sources are Driver, Squires, Rushworth & Wood-Robinson (1994) Making Sense of Secondary Science, "conservation of matter", and Stavy (1990), J. Res. Sci. Teach. 27, on children's conservation across changes of matter (sugar dissolving). Piaget & Inhelder (1974) on conservation of substance and weight is the older root.
| Belief | Named in a lesson | Claim item (bare yes / no) | Bank form |
|---|---|---|---|
| The pieces are lighter than the whole (a crumbled cracker, a crushed thing) | L01: Frances's claim; the cracker case; "Many tiny crumbs can look like less." | L01 q7 (no), q8 (yes, the true pair); PR-5 (no) | PP-23 (cheese puff, reason), PP-24 (twig, true), PP-39 (spread out vs piled up) |
| Mixing makes more (the mass goes up) | L03: Finley's claim; the rice-and-beans case | L03 q4 (no), q7 (yes, true pair); S3 (yes) | PP-32 (sawdust, "packing"), PP-16 (paint) |
| Dissolving makes it lighter / the dissolved thing is gone | L03: Frances's claim; the sugar case | L03 q5 (no), q6 (yes, true pair); PR-9 (no) | PP-33 (bath salts), PP-18, PP-47 |
| Induced belief avoided by wording: "the scale remembers" / "pieces press harder" | never stated as true; appear only as distractors | L01 q9 | PP-8, PP-9 |
The 2 October rules, applied
| Rule (vault note) | Where it bites here |
|---|---|
| Mass, never weight, with gram units | no "weigh / weight" anywhere (grepped: 0); "lighter" only inside a child's quoted belief |
| Units are written as words for young readers | "45 grams" in every sentence; numerals with "g" only on the drawn display and in on-screen cues that name the display |
| Lesson text states the fact, never the topic that taught it | the Grade 3 sentences and Topic 14's lines are stated bare ("Things mixed together are a mixture, and each part of a mixture is still itself.") |
| A coined term is used from then on, with a one-line recap on first reuse | "mixture" recapped once in L03 and recalled by q1; "mass" and "grams" recalled by L01 q1 and PR-1, PR-3 |
| Every sentence has a subject and a verb (S38) | 0 after the fix of five "Why?" bank stems and four fb calculation sentences ("5 + 3 = 8." bare, then the sentence) |
| Never talk a calculation through in prose | every sum is its own line in the article ("25 + 20 + 15 = 60") and in every why |
| A drawn scale gives the readings the lesson uses (setup section) | the empty pan reads 0 said in L01; a cup's reading is the cup with what is in it; every cup goes back on the pan — L03 says so and the cards draw the empty cup beside the full one |
| A reading item shows the instrument, and the marks vary | every reading item carries the drawn scale; item display numbers never repeat (asserted in figures.py: 14, 23, 37, 12/9, 18/26, 140/95, 210/30, 7, 52, 31, 11/17, 48/36, 135/85, 230/25, 115) |
| The headache figure is the teaching figure with the answer's layer off | the three headache cards show the second display as "?"; the verdict chip appears only on teaching cards |
| A verdict mark names its question | every pair card prints "Is the mass the same?" above its chips |
| One depiction per thing, reused everywhere | the digital scale is Grade 3 Topic 17's dscale, the pan balance Grade 3 Topic 18's balance, both imported |
| Code draws what must be exact; David's pack renders what must look real | scales, balances, cards svg; the bar, cracker, clay, cups photo placeholders; the children cartoon placeholders; no hand or person as a glyph |
| No invented apparatus, agents or models in stems | every claim comes from a child at the table; the intro's hike has no sign or notice |
| Connectives carry cause; But opens a turn; if-then named in both halves | "If one crumb falls on the floor, that crumb's stuff is off the pan."; "But all four pieces are on the pan." |
| Say the positive word; no second everyday reading | "stays the same" (never "does not change"); "broke it into pieces", "spread out", "mixed together"; "stuff" beside mass |
| Intro ≤ 120 words, ≤ 3 ?, coins nothing, map line, ready line + poll, never names L01's example | 114 words, 2 question marks, "To find out, we will look at what happens to the mass when a thing breaks into pieces, and when two things are mixed together." |
| Summary opens "Here's everything we found out about …", rules word for word, chips on screen | 96 words; six lexicon sentences; summary_bullets four chips |
| An attached question stands alone; keys spread | six fresh scenes (a bread roll, celery, sand and pebbles, a chopstick, a doughnut, corn and peas); B C B C B A |
| Recognition before recall; a quiz climbs recognise → apply → produce | no coined term; numeric items last in L03 and the practice; L02's scaffold reads the instrument first by design (S32 answered below) |
| An option never bundles a verdict with its reason | lesson claims are bare yes / no; bank claims fix the verdict in the stem and offer four single-statement reasons |
| Hard means more of the skill | every hard bank item carries its "hard because" comment: a produced number from two drawn readings, the rule run backwards, two rules chained, or a reading that breaks the pattern |
| A test item is a fresh instance | the scene-noun grep below; three bank items and one practice item were re-scened after the grep (candy bar → snack bar, chew bar → taffy, a cup of water → a glass / a mug, banana → potato) |
| A character's name belongs to one topic | names run exit 0 (below) |
| Students never see the word strand (S37) | 0; grep -ci strand batch_G4T15.json = 0 |
| US spelling (S14) | color, grams, centimeters: 0 warnings |
Checker: 0 FAIL, 50 WARN (python3 build_tools_check_topic.py grade4/topic15_build/content/G4T15.py)
| WARN | Answer |
|---|---|
| S8 three beats carry 3 sentences (L01 ×2, L03 ×1) | kept: each beat is one screen (the headache; the verdict with its reason); every sentence is short and has a verb; the scripts are 148 / 149 / 149 words |
| S4 long stems: L01 carrot (32), mint candy (33); L02 bagel (35), candle (27); L03 oats FRQ (39), sand (40), pasta (46), salt (42) | kept: the numeric predictions must state two readings and the bookkeeping (both cups back on the pan), which is the skill; the carrot and mint stems carry the boundary (one slice on the floor). None is over 45 words except the pasta item (46), left because its two numbers and the cup line are all load-bearing |
| S13 L01 q5 stem contains key text "5 grams" | kept: the sheet of paper's reading must be stated (no figure); the key is "the same", printed as the number by the option set's design |
| S17 L02 attached stem over 25 words | fixed (24 words) |
| S32 L02 produced answers at positions 2, 3 | kept: type (b) scaffold reads piece 1 and piece 2 off the drawing before the sum; reading the instrument is Grade 3's skill, recalled |
| S32 L03 produced answer at position 3 | kept: the written why follows the what, James's type (c) order |
| S29 units as symbols (1 on-screen cue, 4 alts) | kept: the drawn display prints "8 g" and the cue names what is on screen; Question 3 for James |
| S36 unusual words (35) | fine (US foods and things a nine-year-old knows): yogurt, pizza, pretzel, bagel, muffin, brownie, taco, cucumber, melon, cinnamon, vinegar, granola, pasta, macaroni, waffle, crayon, stapler, celery, wafer, licorice, gummy, hamburger, jello, hike, snack, tortilla, halves, plus, display (Grade 3's word for the scale's window), predicts / prediction (the atom's own verb), heavier (a plain comparative), disappears, milky (now "the water with the milk in it"). Swapped before this run: churro → wooden ruler, biscotti → taco shell, crouton → cheese puff, lentils → gummy bears and jelly beans, pita → hamburger bun, oat bar → snack bar, slab → block, gelatin → jello |
The brief checker (check_brief.py handoff/G4T15/videos/batch_G4T15.json): L01, L02, L03, SUMMARY ✓; INTRO carries the one standing accepted hit (closing: no bullets — an intro teaches nothing and has no rule slide; James, 25 Sep 2026). grep -ci strand on the batch: 0. The batch is NOT sent.
Names run (python3 build_tools_names.py Miss Vance Finley Fiona Frances)
`
Miss free
Vance free
Finley free
Fiona free
Frances free
exit 0
`
All from the Topic 15 row of grade4/NAMES_POOL.md; no other name appears in any student string.
Bank freshness: the scene nouns and the grep
Scene nouns of the lessons, quizzes, attached and summary items: chocolate bar, cracker / crumbs, clay, rice, beans, sugar, cup of water, bean bags, cookie, chalk, carrot, paper, mint candy, toast, pencil, waffle, bread roll, pretzel, granola, bagel, candle, roll, flatbread, breadstick, celery, gummy bears / jelly beans, beads / buttons, oats / nuts, gravel / soil, drink mix, cocoa / milk, peas / corn, honey / tea, sand / pebbles, pasta / macaroni, salt, chopstick, doughnut, tortilla, drink powder.
Grep against the bank and the practice (records run, 2 Oct): every hit inspected. Substring hits only: "bar" (snack bar, taffy — re-scened from candy bar and chew bar), "rice" (licorice), "nuts" (peanuts), "sand" (sandwich), "corn" (corn flakes, cornmeal, cornbread), "shell" (taco shell), "tea" (instead). Real-noun hits kept on purpose, each a different MOVE from the lesson's: soil (the atom's own example, a produced number against the quiz's gravel-into-soil claim), milk (powdered milk as the dissolved thing against the quiz's cocoa-into-milk claim), crumbs (the mechanism word, not a scene), bath salts (a claim against the quiz's salt-into-water reading). Zero hits for every other noun. Practice scenes (fudge, lettuce, potato, cornbread, marbles and shells, jello powder, acorns and pine cones, cucumber, birdseed and sunflower seeds, stapler, stone and cork) appear nowhere else.
Blind bundle (python3 build_tools_blind_bundle.py … grade4/topic15_build/blind/2026-10-02)
bundled: 76 mcq, 23 numeric, 2 frq — adversarial rows 0 — held 101. Every item figure's blind= line is data (the display numbers; what hangs where), never the answer. Grep of the bundle's [Drawing: …] lines for the key words and the typed answers (same|level|answer|lighter|mixture|21|44|235|240|84|28|220|255): 0 hits.
Figures (48; author's review-figures self-check on twelve renders)
Opened at 700–900 px: bar_pair_45, rule_pieces, mix_headache_card, balance_bar_pieces, balance_predict_card, clay_three_pieces, eq_clay, pr_balance_stone_cork, sugar_pair_270, q_pretzel_pieces, cracker_pair_8, pp_lemonade. Two faults found and fixed before hand-over: the balance prediction card drew the two things on the beam (redrawn as the two things on the table with their mass chips; no balance drawn, so no beam gives the answer away) and the "two pieces" balance drew four pieces (a choc_two_pieces drawer added). The drawn sugar was made visible against the cup. Every reading was performed on the render: 45 / 45, 8 / 8, 60 / 60, 25 · 20 · 15, 30 · 15, 180 · 200, 270 / 270, 12 · 9 — each the number the text states. The display guard asserts no two item figures show the same number.
Sentence-atomise self-check (summary per lesson; the fourteen rows run on every idea line, headache, forest line, caption, fb and why)
| Lesson | Ideas counted | One per sentence | Cause → effect | Named actor | Verb carries cause | Explicit link | Chunks ≤ 7 | Longest |
|---|---|---|---|---|---|---|---|---|
| L01 | 25 idea lines, 25 ideas | yes (S1 clean) | the reading before the belief; the belief before the test; the test before the rule | Fiona, Frances, Finley, the scale, the pieces, the crumbs — no bare "it" as subject | snaps, crumbles, brushes, pulls, spreads, reads | "that crumb's stuff is off the pan, so the scale reads a little less" | every subtitle run ≤ 7 lines | 17 words |
| L02 | 25 idea lines, 25 ideas | yes | the pieces' readings before the sum; the sum before the check; the recall before the balance | Finley, Miss Vance, the whole ball, the pans | adds, reads, hangs, balance | "The masses are the same, so the pans hang level." | ≤ 7 | 18 words |
| L03 | 26 idea lines, 26 ideas | yes | the two readings before the mix; the belief before the reading; the reason after the verdict | Frances, Finley, Fiona, the rice, the beans, the sugar | pours, stirs, dissolves, reads | "Frances is not right, because the sugar is still in the water." | ≤ 7 | 16 words |
Every fb ≤ 30 words and every why ≤ 60 words (S5 clean); every why that adds or subtracts shows the line.
Judgement calls
- No coined term. The brief and the atoms coin nothing; "mass", "grams" and "mixture" are recalled, not re-taught. The bank's hard tier is therefore all produced numbers (11 typed) and five hard MCQs, not term recall.
- The cups stay on the pan. The honest way to weigh a mixture without teaching the scale's zero button is to weigh each cup with what is in it and put every cup back; L03 says so in words and draws the empty cup beside the full one. Recorded against the setup section of A drawn scale gives the readings the lesson uses.
- The boundary is taught, not hidden. One crumb on the floor makes the scale read less; L01 says it once under its own subtitle, and two quiz items and three bank items use it. Without it the rule reads as magic and the "pieces are lighter" child has no account of the day the scale did read less.
- Bank claim items take the four-option form (the verdict fixed in the stem, four reasons) because S11 asks four options of every bank MCQ; the lesson quizzes keep the bare yes / no.
- Subtraction items (the rule run backwards) are in the bank and once in the practice; Question 2 for James.
- The pan balance in L02. The atom says "predict the balance reading"; the lesson predicts the digital scale's reading first (the atom's own example) and then the pan balance's verdict, so Grade 3's second instrument is used, not only named.
Owed
- Blind review of the bundle by a reader who has not seen the keys (
blind/2026-10-02/); review-figures and review-questions by a non-author agent; the accuracy pass. - The picture pass (five photo and four cartoon placeholders) waits for James's answer to the questions above.
- The video batch is built and brief-checked, NOT sent: James's word is needed for Grade 4's first batch.
- Not committed: this agent wrote only inside
grade4/topic15_build/andhandoff/G4T15/; the commit is the coordinator's.
v2 — reviews applied (2 October 2026)
Skill: write-lesson (article lines) → write-video-script (the L01 boundary beat) → write-mcqs (every item change) → write-explanation (fb / why / model lines) → sentence-atomise (every new sentence) @ b0fa825
In plain words. Three reviews read Topic 15 cold; every answer key held, and the fixes are to the pictures, the wording and the bank's freshness. The one teaching gap was the video: L01's article said a crumb on the floor makes the scale read less, and two quiz items tested it, but the video never said it — it does now. The "three pieces" card drew five balls; it draws three. Sugar and salt were invisible in their cups; they show now, and an empty cup looks empty. A jar that "reads 0 grams" needed a tare the course never taught; the jar now has a mass. Nine bank items were lesson scenes with the nouns changed; they are re-scened with a different move, one twin is cut, and the clone pairs are marked ⟂. Topic 14's sentences are recalled word for word.
Finding → change
Bank ids in this table are v1's (the ids the three reviews used); the v2 ids, one lower from PP-10 on, are in the Items-changed line below.
| Source | Finding | Change |
|---|---|---|
| Blind | L02-02 / 03 never say which scale holds "piece 1" | stems "the piece on the left scale" / "on the right scale"; q_pretzel_pieces chips THE LEFT PIECE / THE RIGHT PIECE; the whys follow; the blind line names the chips |
| Blind, Review (Essential) | PP-49's jar "reads 0 grams" — a tared scale, untaught | the reviewer's stem word for word: an empty jar of 100 grams; key 315; why "125 + 90 + 100 = 315" |
| Blind, Review | PP-8 / PP-9 twins of L01 q9 | PP-9 (the loaf) cut; PP-8 keeps the pizza with the "lighter" belief in the first distractor as a false mechanism ("The slices are lighter, but the scale adds a gram for each slice.") — see Judgement calls |
| Blind (container convention), Review | no sentence says a cup's reading includes the cup | L03 article and headache: "Each reading is the cup with what is in it." after the two cup readings; the script's screen cue says it too |
| Blind | lesson scenes renamed in the bank | PP-13 → a sausage, the two pieces stated (a different move from L02 q8); PP-17 → orange juice and water; PP-37 → chocolate chips in cookie dough; PP-40 → soap in THREE drawn pieces (40 + 24 + 20); PP-41 → the whole brownie (28) and one piece (11) drawn, the other piece typed (17); PP-46 → three drawn cups (135 + 85 + 55 = 275); PP-47 → the glass's 230 grams drawn, the powder's 25 grams stated, no small cup |
| Blind | clone pairs could both be drawn | ⟂ added: PP-6 / 7, PP-13 / 14, PP-40 / 41, PP-41 / 42 (PP-27 / 28 / 42 and the rest kept) |
| Blind | PP-19 counterfactual option | option D: "The peel has no mass, so the pieces read 165 grams." |
| Blind | PR-03 "volume" possibly unmet | distractor "its length", fb "Length is how long a thing is, measured with a ruler." |
| Blind | "dissolves" is Topic 14's coin | L03 recalls Topic 14's sentence once, word for word, under the sugar case: "A dissolved material is not gone. It is still there, in the liquid." (replacing "You cannot see the sugar, but it is there.") |
| Review (Essential) | L01 video never says the boundary; q4 and q6 test it | new beat 6: "But if one crumb falls on the floor, that stuff is off the pan, and the scale reads a little less." (screen: the cracker card returns, one crumb slides off, 8 g → 7 g); beats 1, 2, 4 trimmed; 148 spoken words by S25 (150 by check_g4_articles.py) |
| Review (Essential), Figures | clay_predict_card drew five balls under "three pieces" | draws clay_three_on_pan, the SAME three circles as clay_all_60 (r 17 / 15 / 13), the display "?" |
| Review | Topic 14's lines paraphrased; "part" for "material" | article: "When two or more materials are mixed together, what you get is called a mixture." / "In a mixture, each material is still itself."; L03 q1 fb and why; lexicon line 6, L03 rule, rule card, closing bullet, summary script and bullet: "Each material is still itself, so the mass stays the same."; every fb / why / model that recalled the sentence now says "In a mixture, each material is still itself" (the word equation keeps "the parts added together") |
| Review | "The powder disappears." | blurb and intro beat 3: "Soon she cannot see the powder." (intro 117 words) |
| Review | S3 was L03 q7's corn and peas | S3: walnuts into dried cranberries, a claim (yes) |
| Review | L03 q3, PP-33, PR-12 are Topic 14 scenes | L03 q3 FRQ: pumpkin seeds and dried cherries; PP-33: instant coffee in cold water; PR-12: dry dog food 120 grams and dry cat food 85 grams |
| Review | PP-16 orange paint is Topic 16's new-colour clue; PP-17 soda water fizzes | PP-16: apple juice and grape juice; PP-17: orange juice and water |
| Review | PP-18, PP-50 count the container or not | PP-18: the reviewer's stem (a mug of water reads 215 grams; 10 grams of powdered milk stirred in), joined to two sentences for S23; PP-50: a fruit salad of 360 grams, the apple 185 grams, no bowl |
| Review | reason clauses in options; a two-clause key | PP-30 D "The pans hang level at first, then the right pan hangs lower."; PR-2 C "neither"; PP-24 key "No stuff was taken away." |
| Review, Figures | crayon pieces drawn as dots | rods(): three blue rod segments 35 / 30 / 25 wide, 8 tall |
| Figures | sugar and salt invisible; full cup = empty cup | SUGAR white with grey grain dots (grains="sugar"); every EMPTY cup's interior shaded EMPTY = #ddd6c8; rice white with grey dashes — on cups_pair_250_20, sugar_pair_270, q_salt_water, cups_pair_180_200, mix_headache_card, mix_pair_380, rule_mix |
| Figures | one brim-full cup held two cups' worth | the mixed cup is heaped above its rim (heap=True, a mound 14 px high) |
| Figures | pr_stapler_115 alt said the reading | scale_fig(..., reading_item=True): alt "A stapler lies on the pan of a digital scale; the display shows a number and the letter g."; the number only in blind; the stapler drawn as a base and a red top arm |
| Figures | pp_lemonade chip clipped; a blue block for a glass | re-scened as a pair card: Grade 3 Topic 16's glass imported (its soda colour swapped for the register's water), 230 g on the left, "?" on the right, chips THE GLASS OF WATER / POWDER STIRRED IN |
| Figures | bar_photo unplaced | L01 article: after the class cartoon, before bar_whole_45, caption "A chocolate bar." |
| Figures (minor) | cookie alt; stapler slab; local eraser; segment lines; clay radii; flat discs; cartoon left/right; internal text | alt "A cookie lies"; the stapler shape; pp_eraser_31 imports Grade 3 Topic 15's eraser; choc_piece() draws the bar's segment lines on both pieces (bar_two_pieces, balance_bar_pieces); clay_bits radii 12 / 10 / 12 / 9 / 10 (569 ≈ 576); pebbles as grey ovals, raisins as dark dots, sand grains, cereal rings, banana-chip ovals; pour_cartoon brief says Frances LEFT, scale RIGHT; the cartoon placeholder reads "Picture to come: …" |
Questions for James — built as recommended
- Sugar in water: kept, with Topic 14's sentence recalled word for word ("A dissolved material is not gone. It is still there, in the liquid.") and "disappears" cut from the intro.
- Subtraction (the rule run backwards): kept in the bank (v2 ids PP-26, PP-27, PP-35, PP-40\, PP-41\, PP-49\*) and once in the practice (PR-7).
- "45 g" on the drawn display: kept; the word "grams" everywhere a sentence is read or spoken.
Counts and key strings (v2)
- Lessons 3 · quiz items 9 + 10 + 11 = 30 · attached 3 + summary 3 · practice 12 · bank 52 (17 easy · 19 medium · 16 hard; MAT4-040 16 (8 / 6 / 2) · MAT4-041 18 (5 / 7 / 6) · MAT4-042 18 (4 / 6 / 8); 11 typed numeric + 5 hard MCQs; ≥ 5 per atom; tags rise with atom order).
- Bank MCQ key positions A 5 · B 12 · C 13 · D 11 (41 MCQs). Attached, video order: B C B C B A (unchanged). L01 three-option 0 1 1 0 1 0 0 · two-option n y. L02 three-option 0 2 1 · two-option y. L03 three-option 0 1 2 · two-option n n y y. Practice MCQ keys 0 0 1 1 2 0 1 1.
- Word counts: articles L01 295 · L02 299 · L03 308 (WARN > 300: the two Topic 14 sentences and the setup line; kept, the reviewer asked for each); scripts 150 · 149 · 149 by
check_g4_articles.py(S25: 148 · 149 · 149); intro 117; summary 96.
Checkers
python3 build_tools_check_topic.py grade4/topic15_build/content/G4T15.py→ 0 FAIL, 47 WARN (v1: 50). Two FAILs met on the way and fixed: L01 script 154 words (trimmed to 148) and PP-17's three-sentence easy stem (joined to two).python3 grade4/check_g4_articles.py grade4/topic15_build/content/G4T15.py→ 0 FAIL.python3 build_tools_names.py Vance Finley Fiona Frances→ all fourfree, exit 0 (the same output as v1's run).python3 build_tools_build_topic_site.py grade4/topic15_build/content/G4T15.py /tmp/g4t15_v2.html→ 3 lessons, 12 practice, 52 pp100, 48 figures. Grader (the page'sgradeTyped, run in node on a key of 45 with the course's accept list, and on the page's own 21-gram and 115-gram items): "45", "45 g", "45g", "45 grams", "45 Grams", "45.0", "45 gram", "forty-five" all accepted; "44", "45 kg", "45 cm", "grams 45" rejected. How:gNormdrops the space between a digit and a letter, so "45 g" and "45g" both become "45g" and match the accept list's "45 g"; the grader does NOT strip units by itself (its unit branch applies only when the stem says "number of grams", as PR-1's does), so every typed item's accept list must carry "N g" and "N grams" — all 23 do (grams_accept()in the bank; hand lists in the quizzes). A word form not listed ("forty five" without the hyphen, on the test item) is rejected; the bank lists both forms.python3 build_tools_video_batch.py …→ 5 videos, key string B C B C B A;check_brief.py→ L01, L02, L03, SUMMARY ✓; INTRO ✗ 1 (the standing closing-bullets line only). Not sent.- Figures re-rendered to
/tmp/g4t15_figs/(SVG and headless-Chrome PNG) and opened:clay_predict_card(three balls counted),sugar_pair_270,cups_pair_250_20,q_salt_water(grain dots visible on white; the empty cup shaded),mix_pair_380,mix_headache_card,rule_mix(the heaped cup; the rule reads "Each material"),pp_lemonade(the glass of water, "?" right),pp_crayon_whole_pieces(three rods),pr_stapler_115,pp_eraser_31,balance_bar_pieces(segment lines),clay_pair_60,q_sand_pebbles,pp_cereal_raisins(three cups),pp_soap_pieces(40 / 24 / 20),pp_brownie_pieces(28 / 11),q_pretzel_pieces(LEFT / RIGHT chips),cups_pair_180_200,bar_two_pieces,pull_cartoon. - Blind bundle re-cut:
grade4/topic15_build/blind/2026-10-02-v2/— 75 mcq, 23 numeric, 2 frq, held 100. Grep of its[Drawing: …]lines forsame|more|less|level|answer|lighter|mixtureand the item figures' key numbers21|44|235|240|84|17|275|255|315: 0 hits. The one display number that is itself an answer, 115, appears in the stapler's drawing line by design (a reading item: the number is the datum the reader needs; the page's alt says only "a number and the letter g").
Items changed (stem, options, key, model, figure, blind text or accept list)
L01-02 · L02-02 · L02-03 · L02-04 · L03-03 · L03-09 · L03-11 · S3 · PR-01 · PR-02 · PR-03 · PR-10 · PR-12 · PP-2 · PP-5 · PP-8 · PP-9 cut · PP-12 (v1 PP-13) · PP-15 (16) · PP-16 (17) · PP-17 (18) · PP-18 (19) · PP-23 (24) · PP-29 (30) · PP-32 (33) · PP-36 (37) · PP-39\ (40) · PP-40\ (41) · PP-45\ (46) · PP-46\ (47) · PP-48\ (49) · PP-49\ (50). Wording only (fb / why, the recalled Topic 14 sentence): L03-01 · L03-02 · L03-04 · L03-06 · L03-07 · L03-08 · PR-08 · PP-31 (32). Every v1 id from PP-10 on is one lower in v2.
Sentence-atomise, the new sentences
Each new student sentence was read for one idea, a named actor, a verb carrying the cause and the plain word first: "Each reading is the cup with what is in it." (one idea; the cup is the subject) · "Soon she cannot see the powder." (Fiona the actor; no "disappears") · "But if one crumb falls on the floor, that stuff is off the pan, and the scale reads a little less." (if … then, the subject named in both halves; "But" opens the contrast) · "The peel has no mass, so the pieces read 165 grams." (a wrong option, one claim) · "The slices are lighter, but the scale adds a gram for each slice." (one false mechanism) · "There are 175 grams of chopped melon in the salad." · the Topic 14 sentences, verbatim, not re-atomised.
Judgement calls (v2)
- PP-8's "lighter" option. The reviewer's wording, "The slices are lighter, but there are more of them.", is a compensation argument (each slice lighter, more slices, the same total) that a careful nine-year-old could defend as the reason, so it would be a second defensible option against "Every slice of the pizza is on the pan." The belief is kept in the distractor as a false mechanism instead. James may prefer the reviewer's wording; it is a one-line change.
- "Part" → "material". The reviewer's row named the L03 article, q1 and lexicon line 6; the same recalled sentence sat in nine fb / why / model lines and the rule card, so all of them now say Topic 14's "In a mixture, each material is still itself" — one word for one thing. The word equation's "the masses of the parts added together" is not the recalled sentence and keeps "parts".
- Re-scenes change the MOVE, not only the noun (the blind readers' complaint was renamed instances): PP-40 three pieces, PP-41 the whole and one piece drawn, PP-46 three cups, PP-47 one reading drawn and one stated, PP-13 the two pieces stated. The display guard still asserts no two item figures share a number (new displays 40, 24, 20, 28, 55; 48, 36, 17, 85 → kept or freed).
- The L03 article is 308 words (> 300 WARN). The three added sentences are the reviewer's and the blind readers'; nothing else was cut to pay for them.
Owed after v2
- A fresh blind read of the v2 bundle (
blind/2026-10-02-v2/) for the changed items only, if the coordinator wants the keys re-agreed; every key is the author's and unchanged except PP-48\ (315), PP-40\ (17), PP-45\* (275). - The picture pass (five photo and four cartoon placeholders) and the video batch send wait on James.
- Not committed: this agent wrote only inside
grade4/topic15_build/andhandoff/G4T15/videos/(the batch and READY.md, rebuilt).
v3 — polish (2 October 2026, after the v2 re-read)
Skill: write-mcqs → write-explanation (the new why and fb lines) → sentence-atomise (every new sentence) @ b0fa825
In plain words. Reader C agreed every key on the v2 bundle and left three soft notes. All three are applied. The four pan-balance items no longer offer a "hangs lower at first, then…" option that no balance does; each offers instead a belief a child holds, that the pan with more pieces, or the pan with the bigger piece, hangs lower. The dissolving item's lemonade powder, the thinnest fresh scene in the bank, becomes protein powder, which no lesson, quiz, practice item or Grade 3 or Grade 4 topic uses (grepped course-wide: zero hits). L02-09's second flatbread now breaks into three pieces, and the stem says the third piece stays on the plate, so a child can see why two pieces hold less than the whole.
| Id | Change | Key |
|---|---|---|
| PP-12 | option D "The pan with more pieces hangs lower."; why adds "There are more pieces on the right pan, but together they have the same mass as the whole sausage." | C, unchanged |
| PP-13 | option D "The pan with more pieces hangs lower."; why adds "There are more pieces on the right pan, but together they have less mass than the whole stick." | A, unchanged |
| PP-25 | option D "The pan with the bigger piece hangs lower."; why adds "The whole bun is the bigger piece, but the two pieces together have more mass." | B, unchanged |
| PP-29 | option D "The pan with the bigger piece hangs lower."; why adds "The whole bar is the bigger piece, but the three pieces together have the same mass." | C, unchanged |
| PP-46\* | "protein powder" for "lemonade powder" in the stem and the why; the figure key pp_lemonade renamed pp_protein_powder (same drawing: the glass of water at 230 grams, "?" on the right; alt names the protein powder) | 255, unchanged |
| L02-09 | stem: "A whole flatbread with a mass of 30 grams goes on the left pan. A second flatbread breaks into three pieces. Two pieces, 15 grams and 10 grams, go on the right pan, and the third piece stays on the plate. What happens?"; the three fb and the why name the piece on the plate; fb C shortened to 25 words after S5 failed the first draft at 31 | B (the left pan hangs lower), unchanged |
Each new distractor was read against its scene: on PP-12 and PP-29 the pans hang level, so neither belief is true; on PP-13 the pan with more pieces (the right) hangs higher; on PP-25 the pan with the bigger piece (the whole bun, left) hangs higher. Each is one statement with no reason clause, the same shape as the three outcomes beside it. The type sheet's Type 7 exemplar (PP-12) and its PP-46 inventory line follow.
Sentence-atomise, the new sentences. "The pan with more pieces hangs lower." (one claim; the pan is the actor) · "There are more pieces on the right pan, but together they have less mass than the whole stick." (the contrast after the fact; "but" opens the turn) · "A second flatbread breaks into three pieces." · "Two pieces, 15 grams and 10 grams, go on the right pan, and the third piece stays on the plate." (two pieces on, one off; the "and" joins the two halves of one placing, read as one picture) · "Level pans mean the same mass." · "Only two pieces of the second flatbread are on the right pan."
Checkers. build_tools_check_topic.py → 0 FAIL, 49 WARN (v2: 47; the two new are S4 on L02-09's stem, 43 words by the checker's count, four sentences, kept because the piece on the plate is the point of the rewrite, and S36 "protein" ×2). check_g4_articles.py → 0 FAIL. Site built to /tmp/g4t15_v3.html (3 lessons, 12 practice, 52 pp100, 48 figures). Blind bundle re-cut to blind/2026-10-02-v3/ — 75 mcq, 23 numeric, 2 frq, held 100; its [Drawing: …] lines grepped for same|more|less|level|answer|lighter|mixture and the item figures' key numbers: 0 hits.
Changed ids (v3): PP-12 · PP-13 · PP-25 · PP-29 · PP-46\* · L02-09. Counts and key strings unchanged from v2.
Owed after v3. A cold read of the six changed ids on the v3 bundle, if wanted; the picture pass and the video batch wait on James. Nothing is committed.
Guidance, questions and accuracy review (2 October 2026)
Skill: course-build → review-lesson (Roles B, B2) → review-questions → review-accuracy (non-author pass; filed by the coordinator from the reviewer's hand-back) @ b0fa825
Topic 15 — guidance, questions and accuracy review, 2 October 2026
A well-built topic whose teaching is right and whose arithmetic is right (every number re-run holds: scripts 146 / 146 / 148, intro 114, summary 96, articles 295 / 299 / 286; 53 items, 17 / 18 / 18 per atom, tiers rising; every sum and difference correct; the eleven typed items all say "grams" and "Type the number"; the claim string balanced; the drawn balance never level before the answer), with three things to fix before it ships and a handful of cheap re-scenes. Two record claims are false on re-performance: "six fresh scenes" (S3 is L03 q7's corn and peas) and "the cup's reading is the cup with what is in it, said in words" (no such sentence in L03).
Essentials. (1) PP-49's jar "reads 0 grams" — a tared scale, untaught; a nine-year-old reads "a jar has no mass". (2) L01's video never says the boundary (a crumb off the pan reads less) but q4 and q6 test it; video and article must each teach the whole part. (3) clay_predict_card draws five balls under "ALL THREE PIECES" (also the figure review's first finding).
The author's three questions, the reviewer's view: (1) sugar in water: keep — Topic 14 sits before 15, "dissolves" is coined, and the scale gives "dissolved is not gone" its proof; recall Topic 14's sentence word for word and cut "disappears". (2) Subtraction: keep — the word equation read the other way, grade-2 arithmetic. (3) "45 g" on the display: keep — Grade 3 drew "150 g" and taught "read the number and the g"; the word everywhere read or spoken.
| where | finding | rule broken | severity | the rewrite |
|---|---|---|---|---|
| PP-49 | jar "reads 0 grams" | a reading true of the setup; no tare taught | Essential | "A cup of vinegar has a mass of 125 grams, and a cup of oil has a mass of 90 grams. An empty jar has a mass of 100 grams. A girl pours the vinegar and the oil into the jar, then puts the jar and both empty cups on the pan. How many grams does the scale read? Type the number." 315; why: "The vinegar and the oil are still themselves, and the jar and both cups are on the pan.<br>125 + 90 + 100 = 315<br>So the scale reads 315 grams." |
| L01 script | boundary in the article only; q4, q6 test it | each channel teaches the whole part (check 52) | Essential | the reviewer's beats; new beat: "But if one crumb falls on the floor, that stuff is off the pan, and the scale reads a little less." (146 words) |
clay_predict_card | five balls, three named | figures tell the truth | Essential | clay_all_60's three circles with the "?" display; alt "A digital scale with three pieces of clay on the pan; the display shows a question mark." |
| L03 article, q1 fb / why, lexicon line 6 | Topic 14's lines paraphrased; "part" for "material" | recalled word for word; one word for one thing | Worth fixing | "When two or more materials are mixed together, what you get is called a mixture." / "In a mixture, each material is still itself." |
| L03 after "the cup of beans reads 200 grams" | setup line missing | the drawn scale's readings | Worth fixing | "Each reading is the cup with what is in it." |
| intro beat 3; blurb | "The powder disappears." | Topic 14's wording rule | Worth fixing | "Soon she cannot see the powder." |
| S3 | L03 q7's scene | fresh instance | Worth fixing | walnuts into dried cranberries, a claim |
| L03 q3, PP-33, PR-12 | Topic 14 item scenes | check 45 | Worth fixing | pumpkin seeds and dried cherries; instant coffee in cold water; dry dog food 120 g and dry cat food 85 g |
| PP-16 | orange paint = Topic 16's new-colour clue | the course against itself | Worth fixing | apple juice and grape juice mixed |
| PP-17 | soda water fizzes | bar list | Worth fixing | orange juice and water |
| PP-18, PP-50 | container counted or not | one reading per item | Worth fixing | "A mug of water on a scale reads 215 grams. A boy stirs 10 grams of powdered milk into the water until it dissolves. What does the scale read now?"; fruit salad 360 g, apple 185 g, melon? (175) |
| PP-8, PP-9 | L01 q9 renamed; twins | check 26 | Worth fixing | cut PP-9; PP-8's option "The slices are lighter, but there are more of them." |
| PP-30 D; PR-2 C; PP-24 key | reason clauses; two-clause key | options carry no reason; key alone two clauses | Worth fixing | "The pans hang level at first, then the right pan hangs lower."; "neither"; "No stuff was taken away." |
pp_crayon_whole_pieces | pieces drawn as balls | figures tell the truth | Worth fixing | three short blue slabs |
| key A 12 %; attached string; PP-45 / PP-51 chain; cheese ×4; L02 q2 / q3 blind line omits the PIECE chips | — | — | Leave | — |
Figure review (2 October 2026)
Skill: course-build → review-figures (non-author pass; filed by the coordinator from the reviewer's hand-back) @ b0fa825 — figures at g3-5-science commit 4ed4f4c
Topic 15 — figure review, 2 October 2026
Two big friendly scales side by side showing the same green number: the lesson's point lands from the picture alone. The second thing a student notices, in L02, is that the "three pieces" card has five balls on it. Every display number matches the text; before/after pairs agree; no item figure draws a level beam; the Grade 3 imports render as Grade 3 drew them; every blind= is data. Six fixes before a cold read, one unplaced key.
clay_predict_carddraws FIVE clay balls (it calls L01'sclay_bits) under a title, chip, caption and alt that say "all three pieces". Drawclay_all_60's three circles (r 17 / 15 / 13).pp_crayon_whole_pieces: the "pieces" are two 4-px dots and a 9-px ball, not a 90-wide crayon broken up. Three blue rod segments (about 35 + 30 + 25 wide, 8 tall), same colour.- Sugar and salt are invisible. SUGAR #fbf3d6 against the cup's #f7f3e8 is one luminance unit apart: in
cups_pair_250_20,sugar_pair_270andq_salt_waterthe small cup looks empty, and the after-card's empty cup is identical to the before-card's full one, so "the sugar is gone from sight" cannot be seen. The record's "made visible" claim is not true on the render. White fill with grey grain dots; every EMPTY cup's top drawn as a shaded interior (~#ddd6c8). The same fix separates rice from the empty cup onmix_headache_card/mix_pair_380/rule_mix. pr_stapler_115is a reading item and its aria-label says "the display reads 115 grams" — the answer to a screen reader. Use Grade 3 Topic 17's reading-item alt ("the display shows a number and the letter g"; the number only inblind) via a flag onscale_fig.pp_lemonade: the right chip runs past the 520 frame (clipped); the "glass of water" is a solid blue block. Shorter chip ("THE CUP OF POWDER") or W=560; draw Grade 3 Topic 16's glass with water below the rim.- Volume truth on the mix cards: two brim-full cups become one brim-full cup of the same size plus an empty one — under a lesson fighting "mixing makes more", the picture says "mixing makes less". Heap the mixed cup above its rim (about half beans), or draw the before cups half full and the after cup full.
Unplaced: bar_photo — place in L01 after the class cartoon, before bar_whole_45, caption "A chocolate bar."
Minor: q_cookie_14 alt "round cookie" vs a bar drawing; pr_stapler a dark slab; pp_eraser_31 and the glass redraw Grade 3 drawers locally (import rule); balance_bar_pieces pieces lack segment lines; clay_pair_60 pieces sum ~27 % larger than the whole; pebbles and raisins flat discs; pour_cartoon brief needs Frances-left / scale-right; placeholder cards carry "the pipeline draws it" (internal text).
| key | kind | used by | verdict | what is wrong | the fix |
|---|---|---|---|---|---|
| l01_class_cartoon, snap_cartoon, pull_cartoon | cartoon | L01 / L02 | OK | — | — |
| pour_cartoon | cartoon | L03 | minor | no left/right | add |
| bar_photo | photo | none | UNPLACED | — | L01 before bar_whole_45 |
| cracker_photo, clay_photo, rice_beans_photo, sugar_water_photo | photo | L01 / L03 | OK | — | — |
| bar_whole_45, bar_headache_card, bar_pair_45, cracker_pair_8, rule_pieces, clay_three_pieces, clay_all_60, eq_clay, bar_two_pieces, eq_bar, balance_predict_card, rule_add_pieces, eq_rice_beans, eq_sugar | svg | L01–L03 | OK | — | — |
| clay_pair_60 | svg | L01 | minor | pieces sum larger | shrink radii |
| clay_predict_card | svg | L02 | FAIL | five balls under "three pieces" | three circles |
| balance_bar_pieces | svg | L02 | minor | no segment lines | add |
| cups_pair_180_200 | svg | L03 | OK | rice faint | whiter rice |
| mix_headache_card, mix_pair_380, rule_mix | svg | L03 | FIX | one brim-full cup holds two; empty = rice cup | heap; shade empty |
| cups_pair_250_20, sugar_pair_270 | svg | L03 | FIX | sugar invisible; full = empty | white + grains; shaded empty |
| q_cookie_14 | svg item | L01 q2 | minor | alt vs drawing | alt "a cookie" |
| q_chalk_23, q_carrot_37, q_pretzel_pieces, q_granola_pieces, pp_muffin_52, pp_brownie_pieces, pp_soap_pieces, pr_balance_stone_cork | svg item | items | OK | — | — |
| q_sand_pebbles, pp_cereal_raisins | svg item | L03 q9 / PP | minor | flat discs | add ovals / marks |
| q_salt_water | svg item | L03 q11 | FIX | salt invisible | white + grains |
| pp_lemonade | svg item | PP hard | FIX | chip clipped; blue block | shorter chip; a glass |
| pp_eraser_31 | svg item | PP easy | minor | local redraw | import G3 T15 eraser |
| pp_crayon_whole_pieces | svg item | PP easy | FAIL | pieces are dots | rod segments |
| pr_stapler_115 | svg item | practice q1 | FAIL | alt states the reading | reading-item alt |
Three best: balance_predict_card, bar_pair_45 with rule_pieces, clay_three_pieces. Three weakest: clay_predict_card, pp_crayon_whole_pieces, sugar_pair_270.
Blind read and v2 re-read (2 October 2026)
Skill: course-build → review-lesson (Role A blind key read, two readers; Role C adjudication by the coordinator) @ b0fa825
Topic 15 — Mass is kept when you break or mix — blind read, 2 October 2026
Every key agreed by two blind readers (101 items each; MCQ disagreements 0; all 23 numeric answers matched the key's integer; both FRQ models in the key's words). No item with two defensible options; no drawing description gave an answer away or lacked the data. The intro poll is not bundled by design.
Flags carried into the fix pass
| Item | Who | Flag | Ruling |
|---|---|---|---|
| L02-02 / L02-03 | A, B | the stem never says which scale holds "piece 1" | "the piece on the left scale" / "on the right scale", and label the pieces in the drawing |
| PP-49 | A, B | "an empty jar that reads 0 grams" is a tared scale, untaught | give the jar a mass, or drop the jar |
| PP-08 / PP-09 | A, B | identical items (pizza / loaf), both L01-09 renamed | cut one, re-scene the other |
| container convention (L03-10, PR-12, PP-15, 34, 48, 51, 53) | B | "a cup of X, N grams … puts the empty cup back" works only if N includes the cup | one sentence in L03's article states the convention |
| lesson scenes renamed: PP-13 (L02-08), PP-17 / 37 (L03-03), PP-40 / 41 (L02-05), PP-46 (L03-09), PP-47 (L03-11); clone pairs PP-06 / 07, 13 / 14, 27 / 28, 40 / 41 | B | fresh instance; a draw could pull both of a pair | re-scene; ⟂ the pairs |
| PP-19 option A | A | counterfactual hard to parse at nine | plainer wording |
| PR-03 "volume" | A, B | possibly unmet | swap the distractor |
| "dissolves" (L03-11, PP-18, 33, 47) | B | Topic 14 coins it | keep; L03 recalls Topic 14's sentence once |
| numeric accept | A, B | bare integer, "N g", "Ng", "N grams" | the grader strips units; confirm on the site |
Readers' files: blind/2026-10-02/READER_A.md, READER_B.md.
v2 re-read, 2 October 2026 (Reader C on blind/2026-10-02-v2, the whole bundle)
Every key agreed (100 items; MCQ disagreements 0; all 23 numeric answers matched the key's integer; both written items in the key's words). No two-defensible items; no figure gives its answer away; no numeric stem has two readings under the lesson's cup convention. PP-25 (pieces outweigh the whole, right pan lower) was worked, not patterned: key B confirmed. Soft notes to the polish pass: the "at first, then…" fourth options on PP-12, 13, 25, 29 are fillers no balance does — mass-based distractors instead; PP-46 (lemonade powder) is the thinnest fresh instance; L02-09's two flatbread pieces sum to 25 against a 30 g whole with no reason given. Reader's file: READER_C.md.