Fold 1
- Ages
- 4–6
- Reading grade
- Pre-K–K
- Stage
- First Reader
- Book
- 6 × 9 in, 24 pp
- Words
- 108
- Words a sentence
- 3.4
- Longest sentence
- 7 words
- Flesch–Kincaid grade
- -0.2
For educators
Six books on one animal, from a child's first book to read alone to popular science for adults. A class can study the same facts with every reader in a book they can manage.
The reading ladder
Measured on each book's reader-facing text with the Flesch–Kincaid formula, the same count the books are checked against before print.
| Measure | Fold 1 | Fold 2 | Fold 3 | Fold 4 | Fold 5 | Fold 6 |
|---|---|---|---|---|---|---|
| Ages | 4–6 | 6–8 | 8–10 | 10–12 | 12+ | 12+ |
| Reading grade | Pre-K–K | K–2 | 1–2 | 2–4 | 4–7 | not graded |
| Stage | First Reader | Read Together | Early Reader | Explorer | Field Guide | Deep Dive |
| Book | 6 × 9 in, 24 pp | 8.5 × 8.5 in, 32 pp | 6 × 9 in, 32 pp | 8 × 10 in, 40 pp | 8 × 10 in, 48 pp | 6 × 9 in, 58 pp |
| Words | 108 | 256 | 534 | 2,123 | 4,529 | 7,296 |
| Words a sentence | 3.4 | 5 | 6.5 | 8.3 | 10.6 | 18.3 |
| Longest sentence | 7 words | 12 words | 10 words | 18 words | 28 words | 44 words |
| Flesch–Kincaid grade | -0.2 | 1.1 read aloud | 0.8 | 3.7 | 5.7 | 9.4 |
Fold 2
- Ages
- 6–8
- Reading grade
- K–2
- Stage
- Read Together
- Book
- 8.5 × 8.5 in, 32 pp
- Words
- 256
- Words a sentence
- 5
- Longest sentence
- 12 words
- Flesch–Kincaid grade
- 1.1 read aloud
Fold 3
- Ages
- 8–10
- Reading grade
- 1–2
- Stage
- Early Reader
- Book
- 6 × 9 in, 32 pp
- Words
- 534
- Words a sentence
- 6.5
- Longest sentence
- 10 words
- Flesch–Kincaid grade
- 0.8
Fold 4
- Ages
- 10–12
- Reading grade
- 2–4
- Stage
- Explorer
- Book
- 8 × 10 in, 40 pp
- Words
- 2,123
- Words a sentence
- 8.3
- Longest sentence
- 18 words
- Flesch–Kincaid grade
- 3.7
Fold 5
- Ages
- 12+
- Reading grade
- 4–7
- Stage
- Field Guide
- Book
- 8 × 10 in, 48 pp
- Words
- 4,529
- Words a sentence
- 10.6
- Longest sentence
- 28 words
- Flesch–Kincaid grade
- 5.7
Fold 6
- Ages
- 12+
- Reading grade
- not graded
- Stage
- Deep Dive
- Book
- 6 × 9 in, 58 pp
- Words
- 7,296
- Words a sentence
- 18.3
- Longest sentence
- 44 words
- Flesch–Kincaid grade
- 9.4
Using the set with mixed readers
Start everyone on one fact
Open the ladder on the board and pick a fact. Each fold tells the same fact in its own words, so the whole class can talk about it together, whatever they are reading.
Hand out by fold, not by name
Children choose the fold that fits them this week and move up when they are ready. Because the facts match, a group reading different folds can still compare notes.
Climb one rung
A confident reader reads a fact in their own fold, then the next fold up, and tells a partner what the deeper version adds.
Let the youngest listen
Where narration is available, Read to me lights each sentence as it is spoken. It suits pre-readers and children new to English.
Trace a sentence to its source
Older students pick a sentence, find its fact in the fact bank and open the source behind it. It is a short lesson in checking what you read.
Fold by fold
Swim, Otter, Swim!
Fold 1 · First Reader · Ages 4–6
What it is for
Read page 3 together first: say the four pictured words, otter, river, fur and rock, and point to each picture. Every other word in the story can be sounded out or is a common sight word such as the, is and has. If a page-3 word stops your child, turn back to its picture; for any other word, sound it out together rather than guessing from the art. Pages 22 and 23 give the facts and sources. To read together, try Fold 2, Hello, Otter!
Talk about it
Start from a chapter:
- Words to know
- The facts behind the pictures
- Kelp, tools and clean rivers
Words
- otter
- It swims.
- river
- water that runs
- fur
- soft hair
- rock
- a stone
Hello, Otter!
Fold 2 · Read Together · Ages 6–8
What it is for
Read aloud and pause for your child to point, answer or join in the sound words; the questions are invitations, not a test. The river otters here are North American river otters, which live in fresh water. Sea otters live in coastal ocean water. Each page names the kind it means, or says “otters” when a fact holds for both. For a child reading alone, try Fold 1, Swim, Otter, Swim!, then Fold 3, Otter: Life in the Water.
Talk about it
Questions the book asks its reader:
- Can you point to the nose?
- Can you kick your feet?
- Can you hug yourself warm?
- Would you like to slide too?
- Where do you like to rest?
- Can you pinch your nose?
Words
This fold has no glossary or word list.
Otter: Life in the Water
Fold 3 · Early Reader · Ages 8–10
What it is for
Read the three pictured words on page 3 together first: otter, river and sea. Then let your child read the book to you. Almost every other word can be sounded out with short vowels, blends, digraphs and silent e. When a word stops them, sound it out together; only for otter, river or sea, turn back to page 3 and its picture. Nina and Theo ask questions along the way. The book keeps river otters and sea otters apart and says which kind each fact is about. Turn the book to read the quiz answers on page 30. Children needing shorter text can start with Fold 1, Swim, Otter, Swim! Fold 4, Otter: A Life in River and Sea, tells the same facts in chapters.
Talk about it
From the book's quiz:
- What does a sea otter use to crack shells?
- What do river otters slide down?
Words
- otter
- a furry animal that swims
- river
- fresh water that runs across land
- sea
- the big, salty water
Otter: A Life in River and Sea
Fold 4 · Explorer · Ages 10–12
What it is for
Fold 4 is for readers of about 10 to 12 who read on their own. Each chapter opens with a big picture, then mixes short text with diagrams, Wow! boxes and questions from Nina and Theo, so a child can start anywhere. The quiz is on page 36 and the glossary on page 37. "How we know" on page 38 shows how scientists found things out, and page 39 lists the sources. For an easier read, try Fold 3, Otter: Life in the Water. For more depth, try Fold 5, Otter: A Field Guide.
Talk about it
From the book's quiz:
- Do otters have blubber to stay warm?
- How do river otters travel fast on snow?
- What do sea otters wrap around themselves?
- Where can a sea otter carry its stone between dives?
- Why are sea otters called a keystone species?
- Can river otter pups swim when born?
Words
- anvil
- A flat stone a sea otter holds on its chest to crack hard shells.
- guard hairs
- Long outer hairs that lock together to keep the underfur dry.
- holt
- A river otter's den along a riverbank or lakeshore.
- keystone species
- An animal that keeps its whole habitat in balance.
- pouch
- A skin pocket under a sea otter's arm for food and stones.
- raft
- A floating group of resting sea otters.
- vibrissae
- Stiff, sensitive whiskers that feel water movements to find food.
Otter: A Field Guide
Fold 5 · Field Guide · Ages 12+
What it is for
Written for readers 12 and up, at a grade 4–7 reading level. Six chapters move from swimming and warmth to river otter life, sea otter life, feeding and tool use, keystone ecology, and conservation. Nina's and Theo's field notes end in questions to talk over, and the Try it boxes suggest hands-off ways to observe. Help your reader keep track of which otter each fact is about: river otters, sea otters, or all otters. For a gentler read, try Fold 4, Otter: A Life in River and Sea; for more depth, try Fold 6, Otters, Unfolded.
Talk about it
Questions the book asks its reader:
- Will you follow their tracks with me along streams and marshes?
- Can you find a track with webbing between the toes?
- What does it bring up each time?
- When does it stop paddling and start to ripple?
- Which works more like a motor, and which more like a steering paddle?
- Why might an animal that swims so well still spend so much time on land?
Words
- anvil
- a hard rock surface an otter uses to break open tough shells
- bioindicator
- a living animal that shows how clean and healthy its home is
- carnassial
- slicing cheek teeth that cut meat like scissors
- countercurrent
- a blood flow path that moves heat from warm arteries to cool veins
- delayed implantation
- a pause in early pregnancy that lets pups be born in a good season
- dorsoventral
- an up-and-down body wave from back to belly
- holt
- a river otter's den, often with an underwater entrance
- keystone species
- a species that shapes its whole habitat, like sea otters in kelp forests
- pelage
- the fur coat that covers the body of a mammal
- raft
- a group of sea otters resting together on the water surface
- reniculate kidney
- a lobed kidney built to filter lots of salt from seawater
- spraint
- river otter droppings used to leave scent marks on land
Otters, Unfolded: The Science of River and Sea
Fold 6 · Deep Dive · Ages 12+
What it is for
Fold 6 is long-form popular science for readers of twelve and up and for adults, with no child guides. Its six chapters cover otter evolution, the physics of fur, diving physiology, tool traditions learned mostly from mothers, trophic cascades, and conservation, and numbered endnotes point to the published sources behind its facts. Younger readers can meet the same six ideas in Fold 5, Otter: A Field Guide.
Talk about it
Start from a chapter:
- The Mustelid That Took to Water
- The Physics of Fur
- Locomotion and the Dive
- The Stone Anvil: Evolution of Marine Tool Use
- Kelp Forests and the Keystone Effect
- The Fur Trade, Decimation, and Recovery
Words
This fold has no glossary or word list.