Accuracy: the course read against Dan’s HS Chemistry review
One finding that matters: the course contradicts itself on rust (Topic 10 says Fe₂O₃; Topics 11 and 12 draw one iron to one oxygen). Topic 12 Lesson 1 renders next, so this card is first.
Nothing forces a Topic 1 re-render. Dan’s “closely packed, not touching” is a convention call, second card. Everything else is one-line fixes, listed on the fourth card for one tap.
Already met: solids vibrate on the spot; evaporation before any “still water” inference; quantitative density; real mixtures; one path per branch in the classification tree; sealed flask on a balance before and after; reversibility never used as evidence; no “stronger” acid. Full record: records/ACCURACY_DAN_HS_REVIEW_2026-10-12.md.
Rust: keep the simple one-to-one drawing and say so, or redraw it two-to-three?
The course says: Topic 10's practice item says rust is Fe₂O₃ and that FeO, the one-to-one compound, is “a different substance, a black powder”. Topics 11 and 12 draw rust as one iron atom joined to one oxygen atom and label it rust.
Why it is a question:
- The course contradicts itself; a student who reads Topic 10 then watches Topic 12 Lesson 1 sees the “black powder” pattern called rust.
- Topic 12 Lesson 1 is “definitely a video” and renders next; Topic 11's figure already carries “drawn simply”.
- The 25 Sep adjudication parked “two iron to three oxygen?” for you; a two-to-three particle (five atoms) does not fit the nine-per-box drawing rule.
Cost of changing it: Keep and caption: one spoken clause in Topic 12 Lesson 1, one caption line in Topic 11, “rust” taken out of the Topic 10 item. Redraw: two figures and the box rule.
My recommendation: Keep the simple drawing; say once that real rust holds more oxygen atoms than iron atoms, in one repeating pattern; drop “rust” from the Topic 10 item.
Particles “touching” in solids and liquids: keep the word and name the convention, or change the lexicon?
The course says: Topic 1's lexicon: “In a solid the particles are packed tightly, touching…”; drawings show circles in contact. Dan: say “closely packed”, not literally touching; touching-circle graphics make a model convention sound like a fact.
Why it is a question:
- At this level the circle is the particle, and a liquid's molecules really are in contact; both readers call it a defensible simplification, not an error.
- The lexicon lines are protected, reused word for word in Topics 2, 3, 5 and 6, and spoken in five Topic 1 videos rendering now.
- One article sentence in Topic 1 Lesson 6 names the convention: “In these drawings, circles that touch show particles packed as close together as they can be.”
Cost of changing it: Keep and name: one article sentence. Change: about 60 strings in five topics and five videos re-rendered.
My recommendation: Keep the lexicon; add the one sentence.
Replace the word “mingled” for mixtures?
The course says: Topic 5 coins a mixture as kinds of particle “mingled”; the word appears in 137 student strings across seven topics (Topic 5: 77, Topic 7: 49). Dan asks for another phrasing.
Why it is a question:
- “Mingled” is an uncommon word for a US twelve-year-old; Topic 5 chose it to avoid defining a mixture with “mixed”.
- Topic 7 has not been rendered yet, so the change costs no re-render today; Topic 5 is the same.
- The replacement in our voice: “mixed together, each still itself” for the coin; “side by side, not joined” on drawings.
Cost of changing it: About 137 strings and one lexicon sentence, before the Topic 5 and 7 batches; nothing if kept.
My recommendation: Replace it before Topics 5 and 7 go to video.
Apply the thirteen one-line fixes from the audit?
The course says: Thirteen fixes that need no ruling: filtering sand instead of coffee grounds and no “clear water”; a crayon on a dashboard instead of a burning candle for melting; two bank items off candle wax; “more concentrated” instead of “stronger” for a drink in Topic 6; “at normal air pressure” once with 100 °C; “faucet” not “tap”; the salt-as-one-particle convention named once; two Topic 9 absolutes given their condition and the hydrogen exception; “sherbet” replaced; the Topic 12 Lesson 1 feedback line; the US food-word list.
Why it is a question:
- Each is one line or one scene; keys are unchanged throughout.
- Three touch scripts about to render: Topic 7's intro, Topic 12 Lesson 1's feedback, and Topic 9 Lesson 6.
- After the fixes: sweeps to zero, a two-reader cold read of every changed item, and the Topic 7 and 12 batches rebuilt from the fixed scripts.
Cost of changing it: An afternoon's fix pass and a cold read; no re-render, because none of these videos exists yet.
My recommendation: Apply all thirteen.