Skill: course-build → write-mcqs → write-explanation, design-check-sequence @ d1a2a04

Topic 34 — Backbone or no backbone — the PP100's nine question types, with their exemplars

What this page is. James approves a bank's question TYPES before the bank is generated (vault: A bank is reviewed as its question types first, one exemplar each, 28 Sep 2026). This sheet writes the exemplars in full, exactly as they sit in content/G3T34.py (PP100, flagged TYPE_SHEET_ONLY). Nine types for three atoms, one exemplar each — under the ceiling of ten, because two of the three atoms are a one-step sort and the third is a three-feature check. No other bank item exists yet. Once the types stand, about fifty items are generated from them, varying the animals, the feature named and the children's names, easy-heavy.

Revised 29 Sep 2026 after the non-author review (REVIEW_G3T34_2026-09-29.md): PP-6's distractors are the topic's taught non-deciders (F20); the inventory below re-reads the practice set, which was re-instanced (F03); the bank's animal pool is listed (F12).

James's rulings applied. Hard items are typed, never MCQs (28 Sep night): two text-entry types — the group's name produced from a description of the feature, and the missing arthropod feature produced from two given ones. Easy and medium are four-option MCQs. No stem leans on a video; no option bundles a verdict with a reason (type 6's stem states the verdict and its options are four single-statement reasons); every stem is a positive question; every exemplar is a fresh instance — no lesson, quiz, attached or practice scene reappears, and no headache character or claim-maker is reused; every drawn animal in the bank will be a photograph with its blind description naming the drawn features, never the group. Nothing James has rejected appears here.

How to read a type line. Each says what the stem asks, what the four options are (the kind of thing), and gives its exemplar scene. Every MCQ has a why (no per-option feedback in the bank; the engine prints Correct / Not quite). Tags follow depth of reasoning: easy = one feature named for two animals, or one animal picked out of four for one feature; medium = the feature run the other way (which animal goes in a named group), two animals matched into one group, the reason for a stated verdict, or the ONE feature three unlike animals share; hard = the group's name produced from the feature's description, or two steps (hold the three features, check off two, produce the third) with the answer typed.

The nine types

Hard because (type 8): the group's name is PRODUCED from the description of the feature, not recognised among options; the description never prints the word. Hard because (type 9): two steps — hold the three features, check off the two the stem gives (no backbone, a hard shell), and produce the third — and the feature is typed. Medium because (type 2): the feature run the other way, from the named group to the one animal that has it, among three that have other coverings. Medium because (type 4): two animals must both pass the backbone test, so four animals are sorted, not one. Medium because (type 6): the student must know which of the three features the named animal lacks; the distractors are the three non-deciders the topic has taught (size, leg count, where it lives). Medium because (type 7): three unlike animals with three different coverings share only what is inside.

Bank notes for the generator. Type 1: vary the feature across the bank (fur, feathers, scales, a shell, wings, six legs); never two animals whose names contain the feature word. Type 3: the vertebrate is always a surprising one (a bat, an eel, a newt, a seahorse), never a cat or a dog — the everyday vertebrates are for type 4's pairs. Type 5: the arthropod varies (a wasp, a lobster, a millipede, a tick) and one distractor always has a hard shell without legs (a slug does not; a mussel or a clam does) so the shell trap is tested. Type 6: the animal always has EXACTLY two of the three features, and the reason names the missing one; the three distractors are the topic's taught non-deciders — size ("It is too big / too small"), leg count ("It has four / eight legs"), where it lives ("It lives on land / in the sea") — never a true-but-irrelevant fact about the animal (review F20). Where the missing feature is a presence (legs, a casing), the positive form is used instead: "Which one of an arthropod's three features is it missing?" with the three features as options (review F21). Type 8: the description names the feature in the lesson's words and never the word "backbone" alone — "a line of bones down the middle of its back, inside" — or, for the invertebrate form, "soft all through, no bones anywhere" → invertebrate. Animal pool for the fifty (review F12): keys drawn from animals no lesson, quiz or practice item uses — wolf, beaver, bat, wasp, trout, armadillo, limpet, newt, seahorse, tick, mussel, barnacle, hedgehog, moth, dragonfly is taken (PR-6), and the lesson animals (snake, worm, fish, cat, turtle, crab, spider, beetle, snail) never as keys. Type 9: the missing feature rotates — no legs (a limpet, a mussel), a backbone present (an armadillo, a tortoise: "type the feature that keeps it out" → "a backbone" needs its own accept list), no hard casing (a slug, an octopus).

Coverage (every atom alone, and the pairs)

At most two alone-types per atom (James: "unlikely that you're going to need more than two question types per atom"). Order in the file: easy PP-1…PP-3 → medium PP-4…PP-7 → hard PP-8, PP-9. Keys of the seven MCQs, in file order: PP-1 A · PP-2 B · PP-3 A · PP-4 C · PP-5 D · PP-6 B · PP-7 B (two A, three B, one C, one D — no letter over 43 %). Typed items: 2 of 9 on the sheet; in a bank of about fifty, types 8 and 9 supply 12–15 typed items on fresh animals.

Design-move inventory (every move on the page, then the bank's)

No bank exemplar shares a move and scene kind with a lesson, quiz, attached or practice item; key animals are new except the lizard, goat and frog, which appear in other moves (review F12); no two exemplars share a move; no headache character (Jethro, Kerensa, Mirren, Inigo, Tallis) and no claim-maker (Lysette, Ulysses, Malachy, Vashti, Anouska, Dimitri, Esteban) appears in the bank; Rosalba is the bank's one name.

The exemplars, in full

Type 1 — PP-1 · LIF3-010 · easy

Stem: A wolf and a beaver share a feature. Which one?

• fur ← key
• feathers
• scales
• a shell

Why: A feature is something you can see on an animal's own body. / A wolf has fur, and so does a beaver. / So the feature they share is fur.

Type 3 — PP-2 · LIF3-011 · easy

Stem: Which of these animals has a backbone?

• a snail
• a bat ← key
• a beetle
• a jellyfish

Why: A backbone is a line of bones down the middle of the back, inside the body. / A bat has one, under its fur. / A snail, a beetle and a jellyfish have no bones inside. / So the bat has a backbone.

Type 5 — PP-3 · LIF3-070 · easy

Stem: Which of these animals is an arthropod?

• a wasp ← key
• a slug
• a frog
• a jellyfish

Why: An arthropod has no backbone, a hard outer casing and jointed legs. / A wasp has all three. / A slug and a jellyfish are soft with no legs, and a frog has a backbone. / So the wasp is the arthropod.

Type 2 — PP-4 · LIF3-010 · medium

Stem: Rosalba makes the group 'has scales'. Which of these animals goes in?

• a goat
• a robin
• a trout ← key
• a bee

Why: The feature is scales. / A trout is covered in scales. / A goat has fur, a robin has feathers, and a bee has a hard casing. / So the trout goes in.

Type 4 — PP-5 · LIF3-011 + LIF3-010 · medium

Stem: Which two animals go in the same group when the feature is 'has a backbone'?

• a lizard and a slug
• a lizard and a spider
• a slug and a goat
• a lizard and a goat ← key

Why: A lizard has a line of bones down its back, and so does a goat. / A slug and a spider have no bones inside. / So the lizard and the goat go in the same group.

Type 6 — PP-6 · LIF3-070 · medium

Stem: An armadillo has a hard shell on the outside and four jointed legs, but it is not an arthropod. What is the reason?

• It is too big.
• It has a backbone. ← key
• It has four legs.
• It lives on land.

Why: An arthropod has no backbone. / The armadillo has a backbone inside, under its shell. / One no is enough. / So the armadillo is not an arthropod.

Type 7 — PP-7 · LIF3-010 + LIF3-011 · medium

Stem: Which feature puts a dog, a frog and a shark in one group?

• fur
• a backbone ← key
• scales
• jointed legs

Why: A dog has fur, a frog has soft skin, and a shark has rough skin. / But inside, each has a line of bones down the middle of its back. / So the feature they share is a backbone.

Type 8 — PP-8 · LIF3-011 · hard · text entry

Stem: A scientist finds a new animal. Inside its body, a line of bones runs down the middle of its back. Type the name of the group it belongs to.

Accept: vertebrate · a vertebrate · vertebrates (the grader folds case)

Why: A line of bones down the middle of the back, inside the body, is a backbone. / An animal with a backbone is called a vertebrate. / So the new animal is a vertebrate.

Hard because: the group's name is produced from the feature's description; the stem never prints "backbone" or the group word.

Type 9 — PP-9 · LIF3-070 + LIF3-011 · hard · text entry

Stem: A limpet clings to a rock. It has no backbone and a hard shell, but it is not an arthropod. Type the name of the feature the limpet must be missing.

Accept: jointed legs · jointed leg · legs · leg · joints · jointed · legs with joints · legs that bend · no legs · it has no legs

Why: An arthropod has no backbone, a hard outer casing and jointed legs. / The limpet has no backbone, and its shell is a hard outer casing. / So the feature it is missing is jointed legs.

Hard because: two steps — hold the three features, check off the two the stem gives, and produce the third — and the feature is typed.