Topic 26 · How a change ripples through a food web — the question types, for your rulings

Skill: course-build → write-mcqs → write-explanation, design-check-sequence @ cca3af6 · exemplar why-lines and the PP-38 note aligned with the bank by the non-author review, 8 Oct 2026 (review-questions @ cca3af6)

Topic 26 — How a change ripples through a food web — 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 (51 items in content/G5T26_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 arrow's direction or one count from a list, or one next-link prediction told in a sentence; medium = a drawn web checked against a list, the direction to follow named, a two-link trace, a reason picked; hard = three links traced, a set of living things picked out, a count produced, the middle link supplied — and rise with the atom's order: LIF5-015 (build the web) nine easy, five medium, two hard; LIF5-016 (the next link) six easy, nine medium, two hard; LIF5-017 (the ripple, the capstone) eight medium, ten 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: NUM4 more / fewer / the same / you cannot tell, whose key is always more or fewer — "the same" and "you cannot tell" are the two real misreadings: the change does not reach the next link, and the web does not let you predict it (adjudication, 8 Oct 2026: "you cannot tell" replaced, the set kept fixed); WAY4 forward, to the eater / back, to the food / sideways, to the plant / both ways at once). No claim items anywhere: the LIF5 register names no belief for these three atoms, and none is invented. Every stem of an easy or medium item is at most two sentences (the S23 rule); only hard items carry three. No option bundles a verdict with its reason. Typed items are counts produced (links away; arrows into a card), each accept list carrying the bare number, the word and the "N links / N arrows" forms; "food web" is Grade 4's two-word term and is recalled by MCQ, never typed. Three multi-selects, each where the answer is genuinely a set. Every item names ONE atom; US spelling; cases named by their animals, never lettered. MCQ keys A 12 · B 15 · C 9 · D 8. KEY TELLS: 0 of 97 MCQs flagged.

The bar list (things a generated item must never use): any lesson scene (the Kansas prairie with its grasshopper, prairie dog, meadowlark, coyote and hawk; Alvin's Minnesota pond with pond weed, tadpoles, minnows, heron and bass; Yellowstone's wolves, elk, willow, grass and beavers); any quiz, attached, summary, practice or recall-bank scene (the Oregon stream: water plants, mayfly, snail, trout, otter; the Arizona desert: jackrabbit, desert mouse, rattlesnake, hawk; the Ohio backyard: caterpillar, rabbit, robin, fox, owl; the Michigan lake: water insects, crayfish, perch, loon, raccoon; the Colorado meadow: vole, marmot, weasel, owl, eagle; the lynx and hares and young shrubs; the deer and leaves; the frog and cricket; owls and mice and acorns; the bobcat, rabbits and clover; egrets and frogs; the roadrunner; the bullfrog and dragonflies; gopher snakes, gophers and plant roots; decomposers, oaks and squirrels; the clover, snails, robins and lettuce; the sea otters, sea urchins and seaweed); "population" (Topic 27 may coin it); "biggest / smallest" for a number; "gravity", "leak", "lift", "snap"; a named child (the topic's three children are headache characters and appear in no item); a non-US animal or place; a decomposer drawn inside a web (Grade 4 drew the mushroom beside the web with no arrow).

The fourteen types

Type	Items	Atom	Tags	Form	The stem asks…	The options / the accept	Exemplar scenes
1	3	015	easy	MCQ	two eats-sentences: which of four arrows belongs in the web, or where the named arrow starts and points	four arrows, every one between things the stem names; exactly one belongs	an Alabama pond turtle; a Maine moose; a Texas sandpiper
2	5	015	easy → hard	MCQ (ordered 1–4) and one typed	from a list of sentences, how many arrows point into (or start at) a card; on a drawing, how many living things eat the plant; a count typed from a five-sentence list (hard)	1 / 2 / 3 / 4; COUNT accept	a South Carolina snapping turtle; Iowa geese and pheasants; a Tennessee kingfisher; the Idaho web; a Wisconsin lake
3	3	015	easy	MCQ	what a finished drawing says about a card with arrows out and none in, or in and none out; what to do when a name is written twice	four statements	the dandelion card; the badger card; the skunk written twice
4	3	015	medium → hard	MCQ, drawn web	the one arrow drawn the wrong way; the one arrow missing; the one listed sentence with no arrow (hard)	four arrows / four sentences	the Idaho web (wolverine and grouse); the Florida marsh (alligator and muskrat)
5	2	015	medium	MCQ, drawn web	which sentence the drawing shows	four sentences, three of them reversed or false	the Florida marsh; the Idaho web
6	9	016	easy → medium	MCQ, the NUM4 set	one living thing goes up or down: what happens to the next link, told in a sentence (easy) or read off a drawn web (medium)	more / fewer / the same / you cannot tell	a Utah pelican; Vermont porcupines; Texas badgers; Florida ghost crabs; Alaska bears; a Nevada sidewinder; Kentucky bats; the marsh and Idaho webs
7	2	016	medium	MCQ, the WAY4 set, drawn web	to predict the next link, which way do you follow the arrow	forward, to the eater / back, to the food / sideways, to the plant / both ways at once	the marsh (water beetle → ibis); Idaho (wolverine → grouse)
8	4	016	medium	MCQ	the correct reason for a stated next-link outcome	four single-statement reasons	an Indiana rat snake; a Montana osprey; a Wisconsin pike; a Nevada sidewinder
9	2	016	hard	multi	the set of eaters with less to eat when one food falls; the set of foods that fall when one eater rises	four living things, two keyed	a Wisconsin lake; a Texas grassland
10	5	017	medium	MCQ, the NUM4 set	two links away, what happens	more / fewer / the same / you cannot tell	Vermont fishers; Georgia catfish; Maine gulls; Iowa skunks; a Tennessee river
11	3	017	medium	MCQ	which living thing changes at the first (or second) link	four living things	Georgia pond; Maine seashore; Vermont forest
12	5	017	hard	MCQ (NUM4) and one multi	three links away, what happens; two links away on a drawn web; the set that ends up fewer after three links	more / fewer / the same / you cannot tell; four living things	Georgia pond; Maine seashore; Tennessee river; the marsh web; Vermont forest
13	2	017	hard	MCQ	the correct reason for an outcome two links away, the middle link left unsaid	four single-statement reasons	Iowa skunks and grubs; Montana ospreys and whitefish
14	3	017	hard	typed	how many links one living thing is from another	LINKS accept (the number, "N links", "N links away")	Vermont forest; Georgia pond; Maine seashore

Hard because — type 2 (PP-50): a count produced from a five-sentence list in which the eater is named in two places. Type 4 (PP-38): every arrow on the drawing read against a five-sentence list. Type 9: a set answer, every arrow out of (or into) the changed card followed, the two-links-away animal resisted. Type 12: three links with the direction decided at each and held to the end; the set of the ones that fall picked out. Type 13: the middle link supplied by the student. Type 14: a count produced, not picked.

⟂ draw constraints (never two on one test): PP-16 ⟂ PP-19 ⟂ PP-21 ⟂ PP-23 ⟂ PP-35 ⟂ PP-38 (the six Idaho drawings: two per test at most); PP-17 ⟂ PP-18 ⟂ PP-20 ⟂ PP-22 ⟂ PP-51 (the five marsh drawings: two per test at most); PP-11 ⟂ PP-28 ⟂ PP-37 ⟂ PP-41 ⟂ PP-47 (the Vermont forest: one of the five); PP-29 ⟂ PP-33 ⟂ PP-42 ⟂ PP-48 (the Georgia pond chain: one of the four); PP-30 ⟂ PP-34 ⟂ PP-43 ⟂ PP-49 (the Maine seashore chain: one of the four); PP-31 ⟂ PP-45 (Iowa skunks: the trace and its reason); PP-25 ⟂ PP-46 (Montana ospreys); PP-32 ⟂ PP-44 (the Tennessee river); PP-15 ⟂ PP-36 (the Nevada sidewinder); PP-12 ⟂ PP-40 (Texas badgers); PP-26 ⟂ PP-39 ⟂ PP-50 (the Wisconsin lake).

One exemplar per type, in full

Type 1 (easy, LIF5-015). A list for a beach in Texas says: the sandpiper eats sand crabs, and the tern eats small fish. Which of these arrows belongs in the food web? — from the sandpiper to the sand crab / from the sandpiper to the tern / from the tern to the small fish / from the sand crab to the sandpiper. Why: The arrow points from the food to the one that eats it. The sandpiper eats the sand crab, so the sand crab is the food. So the arrow runs from the sand crab to the sandpiper. (nearest lesson-side instance: Lesson 1 (Draw a food web from who eats what), question 1, the robin and the worm — a two-option quiz item; here four arrows)

Type 2 (easy, LIF5-015). A list for a swamp in South Carolina says: the snapping turtle eats small fish, ducklings and water snakes. How many arrows point into the snapping turtle card? — 1 / 2 / 3 / 4. Why: Each sentence of who eats what becomes one arrow, from the food to the one that eats it. The snapping turtle eats three foods. So three arrows point into the snapping turtle card. (nearest: Lesson 1 (Draw a food web from who eats what), question 3, the desert hawk's three foods)

Type 3 (easy, LIF5-015). In a finished food web, the dandelion card has three arrows going out and none pointing in. What does the drawing say about the dandelion? — The dandelion eats three living things. / Nothing eats the dandelion. / The dandelion is in the wrong place. / Three living things eat the dandelion. Why: An arrow points from the food to the one that eats it. Three arrows start at the dandelion, so three living things eat it; none points in, so nothing is drawn as the dandelion's food. So three living things eat the dandelion. (nearest: Lesson 1 (Draw a food web from who eats what), question 8 and q9, the card with arrows out and none in)

Type 4 (medium, LIF5-015, drawn web). Here is a food web for a Florida marsh, with one arrow missing. The list says the alligator eats muskrats: which arrow is missing? — from the alligator to the muskrat / from the marsh plants to the alligator / from the muskrat to the alligator / from the water beetle to the alligator. Why: The arrow points from the food to the one that eats it. The alligator eats the muskrat, so the muskrat is the food. So the missing arrow runs from the muskrat to the alligator. (nearest: Lesson 1 (Draw a food web from who eats what), question 6, the desert web with the jackrabbit's arrow missing)

Type 5 (medium, LIF5-015, drawn web). Here is a food web for a Florida marsh. Which sentence does this drawing show? — The water beetle eats ibises. / The alligator eats marsh plants. / The marsh plants eat water beetles. / The ibis eats water beetles. Why: The arrow points from the food to the one that eats it. An arrow runs from the water beetle to the ibis. So the drawing shows that the ibis eats water beetles. (nearest: the recall bank's LIF4-024 reads; here the read is of the drawing against sentences)

Type 6 (easy, LIF5-016). On a Florida beach, the ghost crab eats sand fleas. One summer there are far fewer ghost crabs: what happens to the number of sand fleas? — more / fewer / the same / you cannot tell. Why: The sand flea is the ghost crab's food. Back, the change goes the opposite way. Fewer ghost crabs eat fewer sand fleas, so there are more sand fleas. (nearest: Lesson 2 (Predict what happens to the next link), question 5, the backyard foxes and rabbits — two options there, the four-set here)

Type 7 (medium, LIF5-016, drawn web). Here is a food web for a mountain forest in Idaho. There are more wolverines this year: to predict what happens to the grouse, which way do you follow the arrow from the wolverine? — forward, to the eater / back, to the food / sideways, to the plant / both ways at once. Why: The arrow runs from the grouse to the wolverine, so the grouse is the wolverine's food. From the wolverine to the grouse is back, to the food. So you follow the arrow back. (nearest: Lesson 2 (Predict what happens to the next link), question 1, the stream's trout and otter)

Type 8 (medium, LIF5-016). In a Montana river, the osprey eats whitefish. One year there are far fewer whitefish, and the next year fewer ospreys nest by the river: what is the correct reason there are fewer ospreys? — More ospreys were eaten. / The whitefish ate the ospreys' eggs. / The river had more water in it. / The ospreys had less to eat. Why: The arrow runs from the whitefish to the osprey, so the osprey is the eater. Forward, the change goes the same way: fewer whitefish means less to eat. So the correct reason is that the ospreys had less to eat. (nearest: Lesson 2 (Predict what happens to the next link), question 9, the meadow owls and voles)

Type 9 (hard, LIF5-016, multi). In a Wisconsin lake, the pike eats bluegill and sunfish, and the mink eats bluegill too. One year there are far fewer bluegill. Which living things have less to eat? Select every one. — the pike / the mink / the sunfish / the water plants. Why: Two arrows start at the bluegill: to the pike and to the mink. Forward, the change goes the same way: both eaters have less to eat. The sunfish is not an eater of bluegill, so its food does not change. (nearest: Lesson 2 (Predict what happens to the next link)'s pond, where the heron and the bass both lose the minnows — the taught case; here the set is asked)

Type 10 (medium, LIF5-017). On a Maine seashore, the gull eats crabs, and crabs eat mussels. One year there are far more gulls: two links away, what happens to the number of mussels? — more / fewer / the same / you cannot tell. Why: Link 1: back from the gull to the crab, the opposite way: fewer crabs. Link 2: back from the crab to the mussel, the opposite way: more mussels. So two links away there are more mussels. (nearest: Lesson 3 (Trace the ripple through the web, link by link), question 5, the forest owls, mice and acorns)

Type 11 (medium, LIF5-017). On a Maine seashore, the gull eats crabs, crabs eat mussels, and mussels eat tiny floating plants. The gulls go down: which living thing changes at the second link? — the crabs / the tiny floating plants / the sand / the mussels. Why: A change ripples one link at a time. The crabs are one link from the gull, and the mussels are one link from the crabs. So the mussels change at the second link. (nearest: Lesson 3 (Trace the ripple through the web, link by link), question 6, which changes first in the stream)

Type 12 (hard, LIF5-017). In a Georgia pond, the catfish eats sunfish, sunfish eat water fleas, and water fleas eat tiny floating plants. One year the catfish are gone. Three links away, what happens to the tiny floating plants? — more / fewer / the same / you cannot tell. Why: Link 1: back from the catfish to the sunfish, the opposite way: more sunfish. Link 2: back from the sunfish to the water flea, the opposite way: fewer water fleas. Link 3: back from the water flea to the tiny floating plants, the opposite way: more tiny floating plants. (nearest: Lesson 3 (Trace the ripple through the web, link by link)'s Yellowstone, three links — the taught case; here a fresh chain)

Type 13 (hard, LIF5-017). In an Iowa cornfield, the skunk eats beetle grubs, and the grubs eat corn roots. One year the skunks go down, and the next year there are fewer corn roots left. What is the correct reason there are fewer corn roots? — The skunks ate the corn roots. / More grubs ate more corn roots. / The corn had less rain. / The grubs ate fewer corn roots. Why: Link 1: fewer skunks eat grubs, so there are more grubs. Link 2: more grubs eat more corn roots, so there are fewer corn roots left. So the correct reason is that more grubs ate more corn roots. (nearest: Lesson 3 (Trace the ripple through the web, link by link), question 9, the lake loons, perch and water insects)

Type 14 (hard, LIF5-017, typed). On a Maine seashore, the gull eats crabs, and crabs eat mussels. Type how many links the mussel is from the gull. — accept 2 / 2 links / 2 link / 2 links away / the 2 / the 2 links; wrong_fb for 1 and 3. Why: Gull to crab is one link. Crab to mussel is a second link. So the mussel is 2 links from the gull. (nearest: none on the lesson side — the lesson counts links aloud ("one change rippled three links") and never asks for the count)

Inventory (every item's number, type, atom, tag, form, drawing and scene)

See /tmp-free listing in the build record's "Bank inventory" section; the bank file itself carries type_, d, atom and hb on every item.