Topic 11 · Why the total mass always holds — the question types, for your rulings

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Topic 11 — Why the total mass always holds — the PP100's question types, with their exemplars

What this page is. James reads a bank as its question TYPES first (vault: A bank is reviewed as its question types first, one exemplar each). Under the Grade 5 standing brief the bank is built straight away (52 items in content/G5T11_pp100_bank.py); this sheet is the way in. Each type line says what the stem asks and what the options (or the accept list) are, and prints one exemplar in full. Tags follow depth of reasoning — easy = one fact or a one-step pick; medium = the rule applied to a fresh case, a reason picked, a one-step total or difference produced, an MCQ whose options are numbers (James, 8 Oct 2026: numerical MCQs are medium); hard = two ideas chained, a claim judged by its correct reason, a set answer, a two-step typed number — and rise with the atom's order: MAT5-060 (the general fact) six easy, two medium; MAT5-063 (the routine) four easy, four medium, one hard; SR5-007 (another group agrees) two easy, four medium, two hard; MAT5-061 (dissolving) two easy, four medium, three hard; MAT5-062 (a sealed change of state) one easy, four medium, three hard; MAT5-064 (the capstone: where the missing mass went) one easy, four medium, five hard. Every hard item carries a one-line "hard because" (hb) in the bank file.

Rulings already applied. Four options on every MCQ (fixed sets: the reading set "less than before / the same as before / more than before / you cannot tell from this", ordered, the key moving with the case; the where-did-it-go set; the four-step set, whose key moves; the term set "conserved / dissolved / evaporated / melted"); no option bundles a verdict with its reason (all three bank claims are "X is wrong … What is the correct reason?" with four single-statement reasons; no tier-2 exception used); every easy and medium stem is at most two sentences; drawn readings and tables carry the data and the blind text lists the cells, never the verdict; "conserved" is recalled by MCQ (RECALL_BY_MCQ: nine letters); the typed keys are numbers in grams, their accept lists generated by grams_accept (the bare number, the number with its unit in its written forms, the number in words); two multi-selects, where the answer is genuinely a set; every item names ONE atom; US spelling; units as words in prose, numerals on drawings. MCQ keys A 10 · B 13 · C 12 · D 8. KEY TELLS: 0 of 116 MCQs flagged.

The bar list (things a generated item must never use): "weigh" or "weight" (the scale READS; a student MEASURES the mass); "disappears" (the belief is quoted as "just gone" or "stopped existing" and corrected); "gravity"; "leak", "lift", "snap"; a claim-maker from another topic's row (only Lena, Lila and Lucas, each once in this bank); any lesson scene (the sealed jar with a cracker or a sugar cube; the fizzing tablet in a bottle, capped or open; the cup of water and dish of salt; the jug of water and cup of sugar; the zipped bag of ice; the open pan boiled on the stove); any quiz, attached, practice or recall-bank scene (lunch box of pretzels, tub of butter, jar of drink powder, box of cookies, can of soda, candy bar by a heater; jar of pebbles, bowl of wet sand, sugar cube in a sealed jar, baking soda and vinegar; toy car and ramp, kites, Ohio and Texas classes, can of beans; pitcher of drink powder, mug of tea, bowl of soup, watering can, bath salt; frozen peas, bottle of juice, jar with drops under its lid, bottle in a freezer; wet towel, pot of soup, playground puddle, flat glass of soda, lidded pan, flower vase, bowl over a week; cookie box, ice pop, kettle, thermos of cocoa, cup of tea with a sugar cube; tortilla, coffee, chalk drawing, chip bag, bath bomb, drink crystals, juice pouch, steaming mug, two bowls with wrap, ice cream tub; rice cake, nuts and raisins, apple, paper airplane, rock, bagel, ice cube in a cup, sidewalk puddle, boiling pot; Lucas's open water bottle over the weekend); "biggest / smallest" for an amount; "independent / dependent variable".

The fifteen types

Type	Items	Atom	Tags	Form	The stem asks…	The options / the accept	Exemplar scene
1	7	060, 062	easy, medium	MCQ, the reading set	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	a jar of marbles; a pouch of applesauce; a tin of breadsticks; a cup of yogurt; a bag of snow; a bottle of lemonade; a frozen water balloon
2	2	060	easy, medium	MCQ, the term set	the word for a mass that stayed the same through a change	conserved / dissolved / evaporated / melted	a pencil case; a box of dry spaghetti
3	3	063	easy	MCQ, the step set	what the student does first / next in the routine	measure everything before / make the change / measure everything again / compare	popping candy in a jar; a jar of sand and water
4	3	060, 062	easy → hard	MCQ	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	a jar of honey gone runny; a bag of soft cheese; a sealed jar of warm water with drops under the lid (hard)
5	4	063	easy, medium	MCQ	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	sand and water shaken; a yeast balloon on a jar; dried beans that swell; a group's two readings
6	5	007	easy → hard	MCQ	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	a marble ramp; a class's jar of sugar; a magnet through paper (Maine and Oregon); a counted swing (drawn table); three groups on melting snow (hard)
7	4	063, 007	medium, hard	MCQ	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	a jar of water and a stone; two groups on dissolving salt; one group's shaken jar; a tea bag in a jar (hard)
8	3	061	easy, medium	MCQ	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	a pail of water and pickling salt; milkshake powder in milk; iced tea and lemonade mix
9	2	064	easy, medium	MCQ, the where set	where the missing water went	into the air, as a gas / into the pan / into the table / nowhere, because it stopped existing	a saucer on a heater; a wet swimsuit
10	7	061, 062, 064	medium, hard	numeric, typed	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)	a bowl and a spoon of sugar; a fish tank and fish-tank salt; a foil pouch of chocolate chips; a glass Monday to Thursday (drawn); a bucket of salt water; a foot bath; a can of frozen juice
11	3	061, 062, 064	medium	MCQ	which sentence says why (the pot reads more; the foggy jar reads the same; the dog bowl reads less)	four reasons	a pot of water and salt; a foggy jar; a dog's bowl
12	2	064	medium, hard	MCQ	what left the container	four things	sparkling water gone flat; a stale loaf (hard)
13	3	007, 061, 064	hard	MCQ, claim	X is wrong. What is the correct reason?	four single-statement reasons	Lucas on a careful group; Lila on sugar in cider; Lena on a fish tank
14	2	062, 064	hard	multi-select	select the TWO true sentences	four sentences, two keyed	a sealed bag of melted ice; an open pot of pasta sauce
15	2	064	hard	MCQ	the minimal pair (lid on / lid off) read with both rules; what to count to show the total holds	four sentences / four things	two matching pots (drawn); a mop bucket

Hard because — type 4: the hard-to-spot member (evaporation inside a sealed jar) read against three beliefs. Type 6: whether the second group could share the first group's slip. Type 7: the same-set rule read before any verdict on the mass. Type 10: the rule run backwards (subtraction); two changes of state chained. Type 12: the water hidden inside a solid. Type 13: a documented belief judged by its correct reason. Type 14: a set answer. Type 15: two rules chained on a minimal pair; what left and where it is.

⟂ draw constraints (never two on one test): PP-41 ⟂ PP-42 (two subtraction items on the same move); PP-48 ⟂ PP-50 (the open-pot pair and the open-pot multi: one prints the other's data); PP-39 ⟂ PP-21 (two lid slips); PP-44 ⟂ PP-14 (the dissolved-still-counts belief twice); PP-26 ⟂ PP-27 ⟂ PP-28 (three one-step totals: one per test); PP-9 ⟂ PP-10 (the sand-and-water routine twice).

One exemplar per type, in full

Type 1 (easy, MAT5-060). A sealed glass jar of marbles reads 540 grams, and Lucas shakes it until the marbles are all jumbled up. What does the scale read now? — less than before / the same as before / more than before / you cannot tell from this. Why: The total mass stays the same, whatever change the stuff goes through. The jar stayed sealed, so no stuff was added or taken away. So the scale reads the same as before: 540 grams. (nearest lesson-side instance: Lesson 1 (The total mass holds through every change), question 1, the lunch box of pretzels, three options)

Type 2 (easy, MAT5-060). A sealed pencil case reads 200 grams before and after a pencil inside it breaks in two. Which word says what happened to the mass? — conserved / dissolved / evaporated / melted. Why: When the mass stays the same through a change, we say it is conserved. The case reads 200 grams before and after. So the mass was conserved. (nearest: Lesson 1 (The total mass holds through every change), question 8, the bag of ice, three options)

Type 3 (easy, MAT5-063). Lena wants to check that the mass is conserved when popping candy fizzes in a sealed jar of water. What does she do first? — measure the mass of everything that will be in the test / make the change / measure the mass of everything again / compare the two readings. Why: Measure the mass of everything before the change. So Lena measures the mass of everything that will be in the test first. (nearest: Lesson 2 (Measure the mass before and after the change)-vq1)

Type 4 (hard, MAT5-062). A sealed glass jar of warm water reads 400 grams. Overnight some water evaporates inside, and drops form under the lid. Which sentence about the jar in the morning is true? — The jar reads less than 400 grams, because some water turned into water vapor. / The jar reads 400 grams, because the water vapor and the drops are all still inside. / The jar reads more than 400 grams, because drops were added under the lid. / The jar reads less than 400 grams, because warm water loses mass as it cools. Why: Inside a sealed container, the mass stays the same when ice melts, water freezes or water evaporates. The water that evaporated is water vapor inside the jar, and the drops are that water turned back into liquid. So the water is all still inside, and the jar reads 400 grams. Hard because: the hard-to-spot member, read against three readings that each follow a belief. (every option here is a reading WITH its reason in one frame — the four share one shape, so no option is a bundled verdict against bare ones; recorded as the one type whose options carry a because, all four alike)

Type 5 (easy, MAT5-063). A sealed jar of sand and water reads 730 grams before shaking and 730 grams after. What do the two readings tell you? — The sand lost some mass. / The water gained some mass. / The scale needs fixing. / The mass was conserved. Why: If the two readings are the same, the mass was conserved. Both readings are 730 grams. So the two readings tell you the mass was conserved. (nearest: Lesson 2 (Measure the mass before and after the change), question 3, bare yes / no)

Type 6 (medium, SR5-007, drawn). [pp_table_swing: group one 30; group two 30; group three 31] Three groups count how many times a swing goes back and forth in one minute, and here are their counts. Which result counts for the most? — the third group's result, 31 times / no result, because the groups did not all agree / the first group's result on its own / the result that two groups got, 30 times. Why: When a different group does the same test and gets the same result, the result counts for more. Two groups got 30 times, and one group got 31. So the result two groups got counts for the most. (nearest: Lesson 3 (A result counts for more when another group gets it too), question 4, the Ohio and Texas classes)

Type 7 (medium, MAT5-063). A boy measures a jar of water without its lid at 400 grams, then drops in a stone, screws the lid on, shakes the jar and measures it with the lid at 420 grams. What is the correct reason the second reading is more? — The lid and the stone were not on the pan for the first reading. / Shaking the jar hard made new stuff appear inside it. / A stone gets heavier when it is shaken in water. / A scale always reads more the second time it is used. Why: The same set of things goes on the pan before and after. The lid and the stone were not on the pan for the first reading. So the second reading is more by their masses. (nearest: Lesson 2 (Measure the mass before and after the change), question 4, the lid-off slip)

Type 8 (easy, MAT5-061). A pail of water reads 900 grams and a cup of pickling salt reads 60 grams, and the salt is stirred in until it dissolves. Which two masses give the mass of the salty water? — the water's 900 grams and the salt's 60 grams / the water's 900 grams on its own / the salt's 60 grams on its own / the pail's mass and the cup's mass only. Why: When a solid dissolves in a liquid, the solution's mass is the solid's mass added to the liquid's mass. The salt is the solid, and the water is the liquid. So the two masses are 900 grams and 60 grams. (nearest: Lesson 4 (Add the solid to the liquid: the mass holds when it dissolves), question 1)

Type 9 (easy, MAT5-064). A saucer of water sits on a warm heater with nothing over it, and by evening the saucer reads 40 grams less. Where did the missing water go? — into the air, as a gas / into the pan of the scale / into the table under the scale / nowhere, because it stopped existing. Why: When the reading goes down, the stuff is not gone. It left the container as a gas into the air. The saucer was open, and the water evaporated. So the missing water went into the air, as water vapor. (nearest: Lesson 6 (Where the missing mass went), question 1, the wet towel)

Type 10 (hard, MAT5-061, typed). A bucket of water reads 2,000 grams. A boy stirs in some salt for a science-fair test, and it dissolves. Now the bucket of salty water and the empty salt box together read 2,130 grams. How many grams of salt did he stir in? Type the number. — accept 130 / 130 grams / 130 g / 130 gram / one hundred thirty / one hundred thirty grams / one hundred and thirty / one hundred and thirty grams. Why: When a solid dissolves in a liquid, the solution's mass is the solid's mass added to the liquid's mass. So the solid's mass is the solution's mass take away the liquid's mass. 2,130 − 2,000 = 130, so he stirred in 130 grams of salt. Hard because: the rule is run backwards. (nearest: Lesson 4 (Add the solid to the liquid: the mass holds when it dissolves), question 7, the bath salt)

Type 11 (medium, MAT5-064). A dog's open water bowl reads less every evening than it did in the morning, even on a day the dog is away. Which sentence says why? — The bowl's mass shrinks a little every day. / The water sinks into the floor under the bowl. / Some of the water evaporates into the air during the day. / Water left in a bowl slowly stops existing. Why: When the reading goes down, the stuff is not gone. It left the container as a gas into the air. The bowl is open, so some water evaporates into the air. So the bowl reads less by evening. (nearest: Lesson 6 (Where the missing mass went), question 2, the pot of soup)

Type 12 (hard, MAT5-064). An open loaf of bread is left out for two days, goes stale and hard, and reads 30 grams less than before. What left the bread? — flour, as a powder onto the counter / water, as water vapor into the air / the bread's color, into the air / nothing, because bread cannot lose mass. Why: When the reading goes down, the stuff is not gone. It left the container as a gas into the air. Fresh bread holds water, and the loaf was open to the air. So water left the bread as water vapor into the air, and the loaf reads less. Hard because: the water is hidden inside a solid.

Type 13 (hard, MAT5-064). Lena is wrong to say that the 50 grams of water missing from an open fish tank after a week stopped existing. What is the correct reason? — The fish in the tank drank the 50 grams of water during the week. / The glass walls of the tank soaked up the 50 grams of water. / The water left the tank as water vapor and is in the air of the room. / The water sank down through the tank's base into the stand. Why: When the reading goes down, the stuff is not gone. It left the container as a gas into the air. The tank was open, so water evaporated into the air of the room. So the water did not stop existing, and Lena is not right. Hard because: the belief (MAT5 SD-4: mass disappears when water boils or dries away) is judged by its correct reason. (nearest: Lesson 6 (Where the missing mass went), question 3, Lucas on the puddle, bare yes / no)

Type 14 (hard, MAT5-062, multi). Select the TWO sentences that are true of a sealed bag of ice after the ice has melted. — The bag holds water, the same stuff as the ice. / The bag's mass is the same as before the ice melted. / The bag's mass is less, because melted ice takes up less room. / The bag holds a new liquid that is not water. Why: Ice, water and water vapor are the same stuff: water. Inside a sealed container, the mass stays the same when ice melts, water freezes or water evaporates. So the bag holds water, and its mass is the same as before. Hard because: the answer is a set.

Type 15 (hard, MAT5-064, drawn). [pp_pots_800: a pot with a lid on, 800 g; a pot with no lid, 800 g; both before warming] Here are two matching pots of water, each reading 800 grams before warming. Both are warmed gently for an hour, so that some water in each pot evaporates. Which sentence is true afterward? — The pot with no lid reads less, and the pot with the lid reads 800 grams. / Both pots read less than 800 grams. / Both pots read 800 grams. / The pot with the lid reads less, and the pot with no lid reads 800 grams. Why: In the pot with the lid, the water vapor stays inside. In the pot with no lid, the water vapor leaves into the air. So the open pot reads less, and the lidded pot reads 800 grams. Hard because: two rules chained on a minimal pair. (nearest: Lesson 6 (Where the missing mass went), question 5 and q6, the lidded pan, yes / no on each half)

Draw constraints and notes from the review and the blind read (8 Oct 2026)

• PP-33 ⟂ PP-46: PP-33's stem states that the foggy sealed jar "reads the same as before", which is PP-46's key (the jar reads 400 grams because the water vapor and the drops are all still inside). Never both on one test.
• Tier-2 shape, pending James's 8 Oct reading: PP-39 (type 7, hard) and PP-46 (type 4, hard) each carry four options of ONE frame, a reading or verdict joined to its because. Recorded as the open exception, not an item fault; the lesson quizzes carry none.
• PP-39 re-aimed after the blind read: the stem asks "What do her two readings tell her?" and the key is "That the readings cannot be compared, because the lid was on the pan the first time only."
• PP-49's stem no longer names which pot has the lid; the drawing carries it.