Topic 18 — Which has more? — blueprint (28 September 2026)
What I need from you: 4 decisions
Is L02 "Everything takes up space" placed right, between the mass lesson and the space lesson?
MAT3-062 is new (your ruling on Olivia's comment, 28 Sep). Its prerequisite job is the space comparison in L03, so it sits directly before it; the topic still opens on the surprising case (the small stone that has more mass than the big sponge). The other order, L02 as the topic opener, puts a fact lesson before the "which has more" family the title names.
My recommendation: keep L02 where it is (mass → takes up space → more space → warmer).
May L03 give the word "volume" to an object, after Topic 17 coined it for a liquid?
Topic 17's lexicon says "volume: how much space a liquid fills". L03 says it once, after the rule, as an aside: "Scientists call how much space a thing takes up its volume, the same word as for a liquid." The lessons and items say "takes up more space" (the atom's phrase); no item tests the word (the reviewer's F10, applied).
My recommendation: yes, as the one aside — one word for one thing across the strand, and Grade 5's volume atoms need it for solids.
Does the Celsius-side trap belong in L04, or in the PP100 only?
the register's cross note names "warmer = bigger number only if the same side is read". L04 teaches it in one short part (cup A read on the Fahrenheit side, cup B on the Celsius side; the numbers cannot be compared; read the Fahrenheit side on both). No conversion is asked anywhere; the only skill is "read the same side". It costs the L04 script about 30 words.
My recommendation: keep it in L04; it is the one way a child who has met both sides gets this wrong.
Does "You cannot tell from the balance" stay as the never-keyed fourth option on the balance type?
your Topic 2 ruling allows "you cannot tell" where it is genuinely right. On the cylinder type it now IS the key once (a cork floats: the water cannot show its space) and on the thermometer type once (two readings from different sides) — the reviewer's F8, applied. On the balance no honest instance exists (two objects on two pans always settle), so there it is a fourth option that is never keyed.
My recommendation: keep it on the balance too — it is the belief that a balance cannot compare two different kinds of thing, and the option set then reads the same across the three comparison types.
Topic 18 at a glance — 4 lessons
| Lesson | Opens on | Format | |
|---|---|---|---|
| L01 | Which has more mass? | Here is a small stone and a big sponge. | video + article |
| L02 | Everything takes up space | Here is a table with four squares drawn on it: A, B, C and D. | video + article |
| L03 | Which takes up more space? | Here are two tall glass cylinders with water in them. | video + article |
| L04 | Which is warmer? | Here are two bowls of water. | video + article |
What this topic is, in five lines
Four short lessons, one per atom, in the Matter strand after Topic 17's measuring tools. Each of L01, L03 and L04 is one comparison decided by one instrument: the pan balance (which has more mass), two cylinders of water (which takes up more space), two thermometers read on the same side (which is warmer). L02 is the fact the space comparison rests on: an object takes up a space that nothing else can be in at the same time.
Every instrument is Topic 17's drawing, imported, so the strand keeps one depiction per instrument; the pan balance is new and its register entry is in content/figures.py. Every water level and thermometer level is a whole number of marks on the imported scale (the module asserts it).
The surprising case comes first in L01 and L03 (vault pattern: teach the surprising members before the everyday one) — the small stone has more mass than the big sponge; the marble takes up more space than the bolt that has more mass — so "bigger is heavier" and "more mass is more space" are met head-on before the everyday cases confirm the rule.
Applied without asking (rulings you have already given): hard PP100 items are typed (three of ten exemplars: two text, one numeric); every attached question stands alone with its own drawing; no option bundles a verdict with a reason; every stem a positive question; colour in figures; scene changes spoken with "let's" in the intro and never as an imperative; the intro ends on a ready line and a poll and names no lesson; three questions on the summary; "mass" arrives as "how much stuff" (Topic 17's coinage); the stone-outweighs-sponge fact is stated with no why and "density" is never said; nothing is "weighed", "heavier" or "lifted".
Which has more mass? L01
Here is a small stone and a big sponge.
Which one has more stuff in it?
Amira says the sponge, because it's so much bigger.
Is Amira right?
How could you find out for sure?
A pan balance has a pan at each end of a beam.
Put one object on each pan.
The pan that hangs lower holds the object with more mass.
The stone's pan hangs lower.
So the small stone has more mass than the big sponge.
A bigger object does not always have more mass.
Video: the beam tilting on the word "lower"; the balls of the same size — video and article.
Part 1 — MAT3-004 — Decide which of two objects has more mass from a pan-balance result; coin pan balance
Part 1q — quiz, 12 items
Everything takes up space L02
Here is a table with four squares drawn on it: A, B, C and D.
A red block sits on square B.
Orin has a blue block.
He wants to put it on square B too, right where the red block is.
Can he?
The red block takes up space B.
Nothing else can be in space B while the red block is there.
Every object takes up a space.
An object takes up a space that nothing else can be in at the same time.
Video: the blue block bumping against the red one and stopping; the red block sliding to C — video and article.
Part 1 — MAT3-062 — State that an object takes up a space that nothing else can be in at the same time (Olivia's grid A–D, every object filling its square, one long block filling two; a chair a child sits in)
Part 1q — quiz, 10 items
Which takes up more space? L03
Here are two tall glass cylinders with water in them.
Liv drops a marble into one and a bolt into the other.
The water in each one moves up.
The balance showed that the bolt has more mass than the marble.
So does the bolt take up more space too?
Fill two cylinders with water to the same level.
Drop one object into each.
Each object sinks to the bottom.
The water rises higher for the object that takes up more space.
The marble's water is higher.
So the marble takes up more space, even though the bolt has more mass.
The same level means the same space.
Video: the water tops rising as the objects sink; the before-and-after cylinder with its arrow — video and article.
Part 1 — MAT3-005 — Decide which of two objects takes up more space from the water levels in two cylinders that started level; give volume to an object
Part 1q — quiz, 12 items
Which is warmer? L04
Here are two bowls of water.
Perla puts her left hand in the cold one and her right hand in the warm one.
Then she puts both hands into a third bowl.
Her left hand says the water is warm.
Her right hand says the same water is cool.
One bowl gives two answers.
Which hand is right?
Your hands can be wrong about which is warmer.
Put a thermometer in each one, and read the same side on both.
The bigger number is the warmer one.
The warm tap's thermometer reads 104 °F and the cold tap's reads 54 °F.
So the warm tap's water is warmer.
The same number means the same temperature.
Video: the two speech chips WARM! and COOL! over one bowl; the 30 °C chip fading and 86 °F appearing — video and article.
Part 1 — MAT3-006 — Decide which of two samples is warmer from two thermometer readings taken on the same side
Part 1q — quiz, 12 items
Language decisions
- The atoms' words: "pan balance" (MAT3-004), "takes up space" (MAT3-062, MAT3-005), "warmer" (MAT3-006). Topic 17's words reused, never re-coined: mass ("how much stuff"), temperature, degrees Fahrenheit, the Fahrenheit side, the Celsius side, graduated cylinder, milliliters, digital scale.
- "Scale" names only Topic 17's digital scale; the thermometer's number lines are "sides".
- The stone-outweighs-sponge fact carries no why. "Density" is not said (it belongs to the heavy-for-its-size atom, MAT4). "Heavier", "weighs" and "lifted" are not said; the balance "hangs lower", objects "have more mass".
- Openers vary: L01 "Here's a small stone…", L02 "Here's a table…", L03 "Here are two tall glass cylinders…", L04 "Here are two bowls…"; scripts open on the scene, no title slide; contractions in scripts and headaches.
PP100 type sheet (TYPE_SHEET_ONLY; James's 28 Sep night ruling: hard items are typed)
Nine types, twelve exemplars (type 1 in two forms: the balance and Topic 17's digital scales; types 5 and 7 each with the instance where the setup rule fails and "cannot tell" is the key), at most two alone-types per atom; easy and medium are four-option MCQs, the three hard types are typed (two text entry, one numeric entry). Coverage table in records/TYPES_G3T18.md.
Figures
73 figures; every drawing a reading rests on is SVG (balances, cylinder pairs, thermometer pairs, grids, scale pairs); one photo (the stone and the sponge); two cartoons (the two chairs; the two bowls with Perla's hands). Every figure has an IMAGE_BRIEFS entry and an IMAGE_KINDS entry; people and hands are never drawn as glyphs. Item figures carry the objects' names and no verdict chip; the blind comment gives the tilt, the levels or the marks, never the verdict.
Deliberately not taught
Why the small stone has more mass (density: MAT4); what the balance's tilt has to do with Earth's pull (Topic 3's word is not used here); the sealed / open angle of "a space" (a room, a car, a balloon — the register's second angle for MAT3-062), left for Topic 19's air lessons where it is needed; any Fahrenheit-to-Celsius conversion; subtraction of two water levels (how much space, in mL — a Grade 5 volume atom); sinking and floating as a property (MAT3-007); L03 says once that each object sinks to the bottom, and the only drawn floater is the bank item whose key is "you cannot tell from the water".
This grade’s course architecture — open only if you want the whole map
Skill: course-build → atomise (architecture, step 6b gate) → write-like-james @ acc4fb6
Grade 3 Science — course architecture v3 (James's rulings of 25 September, plus Olivia Mullins's sequencing)
Read this in five minutes. Grade 3 Science is ONE course with a fixed order; nobody picks strands. It arranges the 183 Grade 3 atoms into four strands and forty-two small topics, each with its own mixed practice, summary video and PP100. Nothing below writes a lesson sentence. The atoms stay where they are: the Science Knowledge Graph's 3-5 registers.
Rulings recorded (James, 25 September 2026)
- Strand order: Physics, Matter, Earth & Space, Life. James: "I don't think it matters hugely … Happy to go with 1 Physics 2 Matter 3 Earth and space 4 Life. That works well." Strands may be intermingled later if a reason appears; none does yet.
- Grade 3 is one course. "We're not going to allow students to pick any strand … we need to structure Grade 3 as we think Grade 3 should be structured best." v1's line about students choosing strands was wrong and is gone.
- Topic 1 is the pilot. "That topic 1, I think, works as a good pilot."
- Small topics. "3 atoms is fine for testing. PP100s on quite granular stuff is absolutely fine … A 4-atom topic and a 5-atom topic is great. 9 is too many, really … if something's got 9 atoms, we should be considering splitting it." So sound, soil, fossils and natural resources each stand alone, and every v1 topic of nine or more was split (Card 2). Topics 1 and 2 keep 8 and 7 lessons because James approved Topic 1 as it stands and Topic 2 is one chain about speed; both are flagged as split candidates once their PP100 data arrives.
- Forces opens with Earth's pull and magnets, before the word "force" (Olivia Mullins call, 25 September; James: "I think I'll follow that"). Topics 3 and 4 teach the two non-touching pulls with no talk of forces; Topic 5 coins "force" on both of them and on the hand push together, so the hand push never becomes the whole category. Her two classroom misconceptions (Earth pulls only on your feet; "balanced" is a kind of force) are in the register and the lessons.
- States of matter start with air (Olivia): air takes up space → gases spread → liquids → solids → the sort.
Applied from the earlier rulings: four strands; Motion before Forces before Energy; Scientific Reasoning atoms taught inside the topics that use them; one intro video per strand and per topic, each teaching nothing; one atom, one lesson, both video and article; a summary video before every PP100; PP100 banks of at least fifty items tagged by depth of reasoning; the Forces topics reuse the golden pack; the language rules (Earth's pull, carriers not forms, no "leak" or "lift").
Card 1 — The strands and their order
The call: Physics → Matter → Earth & Space → Life, each with its own intro video and its own end-of-strand test.
| Strand | Topics | Atoms | Why it sits here |
|---|---|---|---|
| Physics | 1-15 | 64 | Motion first: what you can see, before the invisible cause. Energy last: "faster means more energy" needs speed. |
| Matter | 16-21 | 22 (+7 Scientific Reasoning) | Uses the measuring tools and feeds Earth's water cycle in Grade 4. |
| Earth & Space | 22-31 | 41 (+4 Scientific Reasoning) | Weather uses tables and graphs; "the Sun powers Earth" must precede food chains. |
| Life | 32-42 | 43 | Ends the year; leans on Space (the Sun), Forces (Earth's pull) and Matter (properties). |
Scientific Reasoning's 13 atoms are spread through Topics 1, 16, 17, 22, 23 and 25 (Card 4). Total 183 lessons.
Card 2 — The topics
The call: forty-two topics, most of three to six lessons; a mixed mastery practice set, a summary video and a PP100 at the end of every one.
| # | Topic (student-facing title) | Atoms (in teaching order) | Lessons | The big idea it serves |
|---|---|---|---|---|
| Physics | ||||
| 1 | Where is it? Did it move? | MOT3-001, 002, 003, 004, 005, 006, 007, 008 (+ SR3-020, 021 inside L07/L08) | 8 | You say where something is with a landmark; moving means its position changed; motions can repeat |
| 2 | Fast and slow | MOT3-020, 021, 022, 023, 024, 025, 026 | 7 | Faster means farther in the same time, or the same distance in less time |
| 3 | Earth pulls things down | FOR3-021, 029, 030, 028, 022 (+ a closing lesson naming gravity) | 6 | Earth pulls every object, all the time, straight down, on every part of it, without touching; a strong enough pull can beat it; the pull's name is gravity (JM 28 Sep 2026; no word "force" yet) |
| 4 | Magnets | FOR3-023, 024, 025 | 3 | A magnet pulls steel without touching; two magnets pull or push; use a magnet to solve a problem (no word "force" yet) |
| 5 | What a force is | FOR3-012, 001, 008, 006 | 4 | Earth's pull, a magnet's pull and your push are all forces; push or pull; on one object; in one direction |
| 6 | Forces that touch, and forces that don't | FOR3-020, 027, 026 | 3 | Some forces act without touching: Earth, magnets, a rubbed balloon; most pushes touch |
| 7 | Pushes and pulls change things | FOR3-002, 003, 004, 005, 007 | 5 | A push or pull starts, stops, turns or squashes; you can test it |
| 8 | Strong or weak: drawing a force | FOR3-009, 010, 011 | 3 | A stronger push makes a bigger change; an arrow shows a force's direction and strength |
| 9 | Balanced forces | FOR3-040, 041, 042, 043, 045 | 5 | Several forces act at once; balanced forces leave motion as it is, still or steady |
| 10 | Unbalanced forces | FOR3-044, 046, 047 | 3 | Unbalanced forces speed up, slow down or turn |
| 11 | Energy: what has it, how it travels | ENE3-001, 002, 003, 004, 005, 034 | 6 | Energy makes things happen; light, sound and electricity carry it; faster means more |
| 12 | Sound | ENE3-030, 031, 032 | 3 | Sound comes from vibration and travels to your ear |
| 13 | Light: sources, straight lines, shadows | ENE3-010, 011, 012, 017 | 4 | Light comes from a source, travels straight, makes shadows, must reach the eye |
| 14 | Light bounces, bends or soaks in | ENE3-013, 014, 015, 016 | 4 | Reflection, refraction, absorption, sorted |
| 15 | Light and heat | ENE3-020, 021, 033 | 3 | Light-givers give heat; rubbing makes heat; light carries energy |
| Matter | ||||
| 16 | Describe it, sort it | SR3-001, 002, MAT3-001, 002, 003 | 5 | Observe with more than your eyes; describe an object by its properties; sort and order |
| 17 | Measuring tools | SR3-003, 004, 005, 006, 007 | 5 | Thermometer, scale, measuring jug; pick the right one; two groups can disagree |
| 18 | Which has more? | MAT3-004, 062, 005, 006 | 4 | More mass, more space, warmer, decided by a measurement; MAT3-062 "everything takes up space" (JM ruling on Olivia's comment, 28 Sep 2026) sits before the space comparison |
| 19 | Sinks, floats, sticks to a magnet: choosing materials | MAT3-007, 008, 060, 061 | 4 | Test a property, then pick the material for the job |
| 20 | Solids, liquids and gases | MAT3-022, 023, 021, 020, 024 | 5 | Air first: it takes up space; gases spread; liquids take their container's shape; solids keep theirs; then the sort (Olivia's order) |
| 21 | Heating and cooling | MAT3-040, 041, 042, 043, 044, 045, 046 | 7 | Heating and cooling change the state but it is the same water (split candidate: melting/freezing vs evaporating/condensing) |
| Earth & Space | ||||
| 22 | Measuring the weather | EAR3-017, 018, 019, SR3-010, EAR3-020, SR3-011 | 6 | Three instruments, a weather diary, reading it back |
| 23 | Weather over a season, and far away | SR3-012, EAR3-022, 023, 021, 024 | 5 | A season's records make a chart; the chart predicts; other places differ |
| 24 | Volcanoes, earthquakes, landslides | EAR3-007, 010, 008, 011, 009, 012 | 6 | What each one is, then how it changes the land fast |
| 25 | Dangerous weather | EAR3-013, 014, SR3-022 | 3 | Weather can do damage; a defence holds it back; pick the sensible cause |
| 26 | Soil | EAR3-001, 002, 003, 004 | 4 | Soil is broken rock plus dead things |
| 27 | Fossils | EAR3-029, 030, 031, 032, 033 | 5 | A few dead things last as fossils and tell of the past |
| 28 | Using and conserving natural resources | EAR3-040, 041, 042, 043 | 4 | Everything you own started as a natural resource; some run short |
| 29 | The Sun | SPA3-001, 007, 002 | 3 | A huge glowing ball of gas; a star; the source of Earth's energy |
| 30 | The stars | SPA3-003, 004, 005, 006 | 4 | Stars differ; they look like dots because they are far; telescopes show more |
| 31 | The solar system | SPA3-010, 011, 012, 013, 014 | 5 | Earth orbits the Sun with seven other planets; the Moon orbits Earth |
| Life | ||||
| 32 | Alive or not | LIF3-001, 007, 008, 009, 002 | 5 | Living things grow, feed, move and make more; sort living from non-living |
| 33 | What living things need | LIF3-003, 004, 005, 006 | 4 | Food, water, air and a place that suits them |
| 34 | Backbone or no backbone | LIF3-010, 011, 070 | 3 | Grouping by shared features; vertebrates, invertebrates, arthropods |
| 35 | The five vertebrate groups | LIF3-015, 016, 017, 018, 019, 012 | 6 | Mammal, bird, reptile, amphibian, fish, then the sort |
| 36 | Eggs, body parts and senses | LIF3-013, 020, 027 | 3 | Egg-layers or live birth; body parts do survival jobs; animals sense, then respond |
| 37 | How plants make new plants | LIF3-071, 072, 014, 024 | 4 | Seeds, spores, the sort, the flower's job |
| 38 | Plant parts and their jobs | LIF3-021, 022, 023 | 3 | Roots, stem, leaves |
| 39 | Plants respond | LIF3-025, 026, 028 | 3 | Stems grow to the light, roots grow down; plants respond by growing, animals by moving |
| 40 | Life cycles and family likeness | LIF3-030, 031, 040, 041, 042 | 5 | Every life runs in a cycle; offspring take after their parents but differ |
| 41 | Food chains | LIF3-050, 051, 052 | 3 | Every food chain starts with the Sun; remove a link and the rest changes |
| 42 | Living together and coping with change | LIF3-060, 061, 062, 063 | 4 | Groups, places and seasons decide who survives |
Totals: 183 lessons, 42 practice sets, 42 PP100s (banks of at least 50 items each), 4 strand tests (after Topics 15, 21, 31, 42), 1 end-of-grade test.
Why this grouping
- Every prerequisite edge points backwards in this order. Checked atom by atom in the assembled files; no forward reference.
- Animal topics (33-35) and plant topics (36-38) are separate, as James asked; the plant-versus-animal response contrast (LIF3-028) closes Topic 38 because it needs both sides taught.
- Topics 3 and 4 teach Earth's pull and magnets without the word force; Topic 5 coins it on all three kinds (Olivia's sequence). Topic 8 carries the two force-arrow atoms so Topics 9 and 10 can draw balanced and unbalanced forces.
- Topic 24 puts "what a volcano is" straight before "volcanoes change the land fast", and the same for earthquakes and landslides: what it is, then what it does.
What changes: the folder gets grade3/topicNN_build/ per topic; Topic 1's blueprint is approved; Topic 1 is built first.
Card 3 — Topic 1 is the pilot (approved)
The call: pilot "Where is it? Did it move?" end to end — 8 lessons, an attached question per video, a ten-item quiz after each, mixed practice, summary video, PP100 — before any other topic starts.
- It is the first thing a Grade 3 student meets, so the whole format ladder gets tried where the stakes are lowest.
- It holds a fact, four sorts, two routines and a prediction. Every check type the course needs appears once.
- Its quiz items are drawings of everyday scenes, so the figure pipeline for young grades gets tested too.
- Topics 3 to 10 follow, reusing the golden Forces pack where its lessons match (push or pull, force on one object, strength, direction, more than one force, the balanced and unbalanced lessons).
Card 4 — Scientific Reasoning is taught where it is used
The call: each of the 13 Scientific Reasoning atoms is a lesson inside the topic that first needs it, with its check there; no separate strand, no separate test.
| SR atom | Host topic | Why there |
|---|---|---|
| SR3-001 Observe with more than your eyes; SR3-002 Observation or idea about it? | 16 Describe it, sort it | describing an object's properties is observing |
| SR3-003 Read a thermometer; SR3-004 Measure mass with a scale; SR3-005 Measure the volume of a liquid; SR3-006 Pick the right measuring tool; SR3-007 Two groups, two different answers | 17 Measuring tools | the tools before "which has more?" uses them |
| SR3-010 Record results in a table; SR3-011 Find a value in a table | 22 Measuring the weather | the weather diary is the first table students fill and read back |
| SR3-012 Read a pictograph or bar graph | 23 Weather over a season | the graph before the graphing routine |
| SR3-020 Spot the pattern; SR3-021 Use the pattern to predict | 1 Where is it? Did it move? (inside L07 and L08) | the swing's repeat is the pattern |
| SR3-022 Choose the sensible cause | 25 Dangerous weather | first place students pick a cause for an event |
Card 5 — Tests and benchmarks
The call: a PP100 per topic; a static end-of-strand test per strand (some free response); one static end-of-grade test; all Grade 3 tests are our own banks, seeded from released grade-5 items filtered to Grade 3 atoms.
- No state tests science before grade 5 (D1 ruling). The released STAAR, Florida SSA and AZSCI grade-5 forms give the style and difficulty; items tagged to Grade 3 atoms seed the banks.
- The strand tests fall after Topics 15, 21, 31 and 42.
- The end-of-grade test samples all four strands with free-response items.
What happens next
Topic 1 is built as the first interactive version for James: the topic intro (video script and article), eight lessons each as a video script with animation guidance and an article with figures, one attached question per video, a ten-item quiz per lesson, mixed practice, the summary video script and the PP100 bank. Topic 3 follows, reusing the golden pack.