Skill: write-like-james @ cca3af6 · the build: write-lesson, write-mcqs, write-video-script, write-summary, write-intro @ cca3af6; the non-author review (review-lesson Role B with review-questions, review-figures, review-accuracy) applied @ cca3af6
Topic 11 "Why the total mass always holds" — your read (8 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 The total mass holds through every change | MAT5-060 | The total mass stays the same, whatever change the stuff goes through. No stuff was added, and no stuff was taken away. The mass is conserved. |
| L02 Measure the mass before and after the change | MAT5-063 | Measure the mass of everything before the change. Make the change with everything still together. Measure everything again. The same two readings: the mass was conserved. |
| L03 A result counts for more when another group gets it too | SR5-007 | One group's result could be a slip. A different group does the same test and gets the same result. Then the result counts for more. |
| L04 Add the solid to the liquid: the mass holds when it dissolves | MAT5-061 | The solution's mass is the solid's mass added to the liquid's mass. The dissolved solid is still there, so it still counts. |
| L05 The mass holds when the state changes inside a sealed container | MAT5-062 | Inside a sealed container, the mass stays the same. Ice melts, water freezes or water evaporates. The stuff is still water, all still inside. |
| L06 Where the missing mass went | MAT5-064 | When the reading goes down, the stuff is not gone. It left the container as a gas into the air. Count the air too, and the total mass still holds. |
The intro script (115 words, about 58 s)
Here's Lucas in Miss Kowalski's class. On Friday he filled his water bottle, left the cap off, and put it on a digital scale: four hundred grams. Then he went home for the weekend. On Monday nobody has touched the bottle, but the scale reads three hundred seventy grams. Thirty grams of water have gone. So where did they go? And if Lucas had put the cap on tight, would the number have dropped at all? To find out, we will look at what a scale reads before and after a change, and at what happens to the stuff when the number drops. Okay, so are you ready to find out where the water went?
The question types (from TYPES_G5T11.md)
- Type 1 (easy, medium · MCQ, the reading set · 060, 062): what the scale reads after a change inside a sealed container (a shake, a squeeze, a melt, a freeze, a thaw) — less than before / the same as before / more than before / you cannot tell from this
- Type 2 (easy, medium · MCQ, the term set · 060): the word for a mass that stayed the same through a change — conserved / dissolved / evaporated / melted
- Type 3 (easy · MCQ, the step set · 063): what the student does first / next in the routine — measure everything before / make the change / measure everything again / compare
- Type 4 (easy → hard · MCQ · 060, 062): which sentence says why the reading held, or tells you the mass is conserved, or is true of the jar in the morning — four sentences
- Type 5 (easy, medium · MCQ · 063): what two matching readings tell you; what to measure after; what to ask when the readings differ — four statements / four things to measure / four questions
- Type 6 (easy → hard · MCQ · 007): how much the result counts now; which thing makes it count for more; which result counts for the most — for more / for less / the same…; four actions; the groups' results
- Type 7 (medium, hard · MCQ · 063, 007): the correct reason: why the second reading is more (the lid slip); why two groups' result counts for more; why one result could still be wrong; what happened when the lid was forgotten (hard) — four single-statement reasons
- Type 8 (easy, medium · MCQ · 061): which two masses give the solution's mass; which sentence is true of a dissolved powder; the total as a number — two masses / four sentences / 330 grams among 300, 30, 270
- Type 9 (easy, medium · MCQ, the where set · 064): where the missing water went — into the air, as a gas / into the pan / into the table / nowhere, because it stopped existing
- Type 10 (medium, hard · numeric, typed · 061, 062, 064): the solution's total (medium); the reading after a sealed change (medium); the difference that went into the air (medium, drawn); the solid's mass from the total and the liquid (hard); two changes chained in a sealed can (hard) —
grams_accept(n) - Type 11 (medium · MCQ · 061, 062, 064): which sentence says why (the pot reads more; the foggy jar reads the same; the dog bowl reads less) — four reasons
- Type 12 (medium, hard · MCQ · 064): what left the container — four things
- Type 13 (hard · MCQ, claim · 007, 061, 064): X is wrong. What is the correct reason? — four single-statement reasons
- Type 14 (hard · multi-select · 062, 064): select the TWO true sentences — four sentences, two keyed
- Type 15 (hard · MCQ · 064): the minimal pair (lid on / lid off) read with both rules; what to count to show the total holds — four sentences / four things
Six lessons for six atoms in Miss Kowalski's class, with Lena, Lila and Lucas.
Lena shakes a sealed jar until the cracker is crumbs and until the sugar cube is gone from sight, and the scale reads the same number each time, so L01 teaches that the total mass stays the same whatever change the stuff goes through; "conserved" is the one new word, coined there.
Lila checks it properly on a fizzing tablet in a capped bottle (L02: measure everything before, make the change with everything still together, measure everything again, compare).
Lucas says a careful group need not be checked, and two more groups' matching readings show why he is not right (L03: a result counts for more when another group gets it too).
Lena predicts the salty water's mass by adding the salt's mass to the water's (L04: the dissolved solid still counts), and Lila's zipped bag of ice reads 120 grams melted, frozen and partly evaporated inside (L05).
Lena boils an open pan and says 80 grams of water are "just gone"; the same bottle with its cap off, and the pan, show that the stuff left as a gas into the air, and the total still holds once the air is counted (L06, the capstone).
"Mass" is said and "weight" never; nothing "disappears"; Grade 3's digital scale and Grade 4's dissolving and mixing sentences are recalled word for word.
The non-author review is applied (one must-fix, ten worth-fixing); the two cold readers are next. Pictures are placeholders until the text is clean and read.
Questions for James
none
Applied without asking
The bottle pictures in L06 now match what L02 taught. L02's 350 grams is the bottle, its cap and the tablet together on the pan, and L02's one trap is "the same set of things both times". L06 had drawn "the same bottle" at 350 grams before the fizzing as a lone bottle, and the cap-off "after" with the cap nowhere — the slip L02 warns about. Both pairs now open on L02's own before drawing (bottle, cap and tablet on the pan), the cap stays on the pan when the bottle fizzes open, and one line says so: "The cap lies on the pan both times, so only the gas is missing from the second reading." Revert: restore the two drawer lines named in REVIEW_G5T11_2026-10-08.md row 1 and delete the article line.
The L02 video now says the line its quiz keys on. "If they differ, something was added or taken away." joins the rule beat (three beats trimmed by a word each; 150 words). Hot water just off the boil was said to send up "no water vapor"; the water now cools first.
Items. Two item drawings had their readings repeated in the stem, so the drawing did no work (L02-q6, L06-q8; PP-49 likewise named the lidded pot the picture shows) — the stems now send the child to the display. One key sat between two mirror-image distractors (L03-q4, re-formed as "how much does the Ohio class's result count now?"). Nine distractors no child would pick ("the vase's shadow", "the mug's handle", "larger letters on the board", "the teacher's opinion"…) are now errors children make ("up to the Sun", "the air inside the jar turned into water", "nothing, because the soda just stopped fizzing"). Four distractors said "heavier / lighter / heavy" in a topic whose rule is mass, never weight; they say mass now. Five bank items were L02's quiz scenes with the nouns changed (sand for pebbles, a stone for pebbles, popping candy for the tablet) and are re-scened (a crayon melting in a sunny jar; flour and water squeezed into dough in a sealed sandwich bag; maple syrup stirred into a lidded travel cup). Two grown-up idioms in L03 ("rule out", "dismiss") became "nobody can be sure there was no slip" and "harder to doubt". One quiz item that leaned on the item before it ("The same pan…") stands alone. No key was wrong.
The lessons
Also on the site
Topic intro and poll · summary and three questions · mixed practice · the PP100 bank · the type sheet
After you answer
Nothing waits on an answer. The two cold readers read blind/2026-10-08-reviewed next; then the picture pass starts on the six cartoon placeholders and the one photo placeholder; the batch is built and checked and waits for your taps on the six scripts (this topic is in your Matter review sample).
What the review found, and what changed
The non-author review (8 October): 36 findings, 11 applied
Must-fix (1, applied): L06's bottle pairs drew a 350-gram reading of a different set of things from the one L02 measured. Worth fixing (10, all applied): the L02 video's missing "if they differ" line; hot water off the boil sending up "no water vapor"; two item drawings (and one bank drawing) repeated in their stems; a key the odd shape out; nine silly distractors; four weight words; five renamed-template bank items; two idioms; one item leaning on the item before it. Simplification-leave (10): the open bottle's 2-gram drop (one tablet gives about a gram; readable on the display, the author's named simplification); "the same bottle" fizzing twice; bubbles drawn after the fizzing stops; water showing through the pan wall; a shaken closed can "fizzing" unseen; a gas balloon's buoyancy; milkshake powder "dissolving"; phone-width text on the imported pair and rule cards (course-wide drawers); the same-case what → why pair in L01; the vase's flowers drinking some water. Not an error (15): the author's six calls ("conserved" as the one required term; Grade 3's "digital scale"; the worked-line form; L06's two minimal pairs; L03 without a video; the zipped bag through L05), the bank's "X is wrong… correct reason" form, the two tier-2 reading-with-because items (your 8 October reading pending), the intro's "have gone", the two documented claim openers, every number recomputed, every accept list, the order item, the two multi-selects, the five blind lines. The ten Grade 4 root causes were looked for one by one: two idioms (fixed), nothing else. Full table: REVIEW_G5T11_2026-10-08.md.
Gates after the fixes: check_topic 0 FAIL (S46 B = C = D = 0); check_terms no hits; check_g5_articles 0 FAIL (scripts 147 / 150 / 148 / 150 / 150 / 150); check_key_tells 0 of 116; check_svg_ids PASS (37 figures); check_lessons 0 FAIL, S118 0 FAIL 2 WARN (by design); the blind bundle re-cut to blind/2026-10-08-reviewed/ (104 mcq, 13 numeric, 1 frq, 1 order, 2 multi; 0 verdict words in its five drawing lines); the batch rebuilt and check_brief.py clean except the two standing notes. Not sent.
The records, in full
The build record (v1, 8 October) and the review record
The author's record: BUILD_RECORD_G5T11.md (its key strings and L06 article count predate the review; L03's 3-option string is now C C C A B B and L06's article 297 words). The review: REVIEW_G5T11_2026-10-08.md. The type sheet: TYPES_G5T11.md.