Fold 1
- Ages
- 4–6
- Reading grade
- Pre-K–K
- Stage
- First Reader
- Book
- 6 × 9 in, 24 pp
- Words
- 105
- Words a sentence
- 3.6
- Longest sentence
- 7 words
- Flesch–Kincaid grade
- -0.9
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, 64 pp |
| Words | 105 | 223 | 492 | 2,181 | 5,046 | 8,057 |
| Words a sentence | 3.6 | 4.6 | 6.1 | 7.3 | 10.2 | 14.8 |
| Longest sentence | 7 words | 11 words | 10 words | 15 words | 22 words | 32 words |
| Flesch–Kincaid grade | -0.9 | -0.2 read aloud | 0.5 | 3.2 | 6.4 | 10.7 |
Fold 2
- Ages
- 6–8
- Reading grade
- K–2
- Stage
- Read Together
- Book
- 8.5 × 8.5 in, 32 pp
- Words
- 223
- Words a sentence
- 4.6
- Longest sentence
- 11 words
- Flesch–Kincaid grade
- -0.2 read aloud
Fold 3
- Ages
- 8–10
- Reading grade
- 1–2
- Stage
- Early Reader
- Book
- 6 × 9 in, 32 pp
- Words
- 492
- Words a sentence
- 6.1
- Longest sentence
- 10 words
- Flesch–Kincaid grade
- 0.5
Fold 4
- Ages
- 10–12
- Reading grade
- 2–4
- Stage
- Explorer
- Book
- 8 × 10 in, 40 pp
- Words
- 2,181
- Words a sentence
- 7.3
- Longest sentence
- 15 words
- Flesch–Kincaid grade
- 3.2
Fold 5
- Ages
- 12+
- Reading grade
- 4–7
- Stage
- Field Guide
- Book
- 8 × 10 in, 48 pp
- Words
- 5,046
- Words a sentence
- 10.2
- Longest sentence
- 22 words
- Flesch–Kincaid grade
- 6.4
Fold 6
- Ages
- 12+
- Reading grade
- not graded
- Stage
- Deep Dive
- Book
- 6 × 9 in, 64 pp
- Words
- 8,057
- Words a sentence
- 14.8
- Longest sentence
- 32 words
- Flesch–Kincaid grade
- 10.7
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
Go, Penguin, Go!
Fold 1 · First Reader · Ages 4–6
What it is for
Read the Words to know page together first: penguin, black, wings and egg, each with its picture. Every other word in the story is either a short word to sound out or a common sight word such as the, is or you. Let your child point to each word and take their time. When one of the four taught words stops them, turn back to page 3 and its picture; for any other word, sound it out together rather than guessing from the picture. The age band is a guide, not a promise that every child is ready. Pages 22 and 23 give adults the facts and sources behind the pictures. For a longer book to read together, try Fold 2, Hello, Penguin!
Talk about it
Questions the book asks its reader:
- Can you see it?
- Can you dip and zip?
Words
- penguin
- a bird
- black
- dark, like ink
- wings
- It swims with them.
- egg
- Penguins keep it warm.
Hello, Penguin!
Fold 2 · Read Together · Ages 6–8
What it is for
Read aloud and pause for your child to point, answer or join in a sound word. The sound words are play, not penguin calls. Every penguin in the pictures is an emperor penguin, but kinds of penguins live and raise chicks in different ways; these notes say which facts fit all penguins and which fit only some. Next, try Fold 3, Penguin: Wings for the Sea.
Talk about it
Questions the book asks its reader:
- Can you point to the beak?
- Where can it go?
- Can you see it?
- Can you find a bird in the middle?
- Can you spot the chick?
- Can you find the chick's beak?
Words
This fold has no glossary or word list.
Penguin: Wings for the Sea
Fold 3 · Early Reader · Ages 8–10
What it is for
Read the three pictured words on page 3 together first: penguin, flipper and feather. Then let your child read the story to you. If penguin, flipper or feather stops them, point back to that word and its picture on page 3. Sound out every other word together; a few, such as bird, warm, food and feet, use letter patterns taught later, so read those for them. Zara and Eli ask questions along the way. The pictures on pages 24 to 26 show Galapagos penguins; every other penguin scene shows emperor penguins. The words say when a fact applies to only some penguins. Turn the book upside down to read the quiz answer on page 30. Children needing shorter text can start with Fold 1, Go, Penguin, Go! For a longer book in chapters, try Fold 4, Penguin: A Life Between Ice and Sea.
Talk about it
From the book's quiz:
- Can a penguin fly?
Words
- penguin
- a bird that swims
- flipper
- a penguin wing
- feather
- part of a bird's coat
Penguin: A Life Between Ice and Sea
Fold 4 · Explorer · Ages 10–12
What it is for
This book is for readers of about 10 to 12. Read a chapter at a time, or start with a picture. Help with new words as needed. The quiz is on page 36 and the glossary on page 37. Page 38 explains how to think about evidence. The pictures show emperor penguins unless a caption names another kind. A reading age is a guide, not a promise about every child. For more depth, try Fold 5, Penguin: A Field Guide.
Talk about it
From the book's quiz:
- Where does an emperor father hold his egg?
- How does a winter huddle help emperor fathers?
- Where does a parent carry food for its chick?
- Which body parts drive a penguin through water?
- Why must a diving penguin come up?
- What pattern may help a penguin blend in?
Words
- countershading
- A pattern with a dark back and a light front.
- down
- The fluffy feathers that cover a growing chick.
- flipper
- A penguin's flat wing, used for swimming.
- food web
- Feeding links between living things.
- incubation
- Keeping an egg warm while the chick grows inside.
- krill
- Small sea animals that look like shrimp. Some penguins eat them.
- molt
- The change from old feathers to new ones.
- preening
- Caring for feathers with the bill.
Penguin: A Field Guide
Fold 5 · Field Guide · Ages 12+
What it is for
This field guide is for readers 12 and up. Read a chapter together, then talk through the field notes and Try it boxes. Ask which species each claim describes, and whether scientists observed it or inferred it. The glossary is on page 43 and the index on page 44. For a gentler start, try Fold 4, Penguin: A Life Between Ice and Sea; to go further, read Fold 6, Penguins, Unfolded.
Talk about it
Questions the book asks its reader:
- Can you leave space for the species name at the top of each notebook page?
- Will you look closely with me before we explain anything?
- Will you ask with me what the evidence shows, and keep a space for questions that still need an answer?
- In a swimming clip, can you trace the wing tips first and then watch the feet?
- When a bird touches its feathers with its bill, what would tell you it is preening?
- How many pictures would you need to show how a huddle changed?
Words
- buoyancy
- the upward force of water that a diving penguin must work against
- countershading
- a dark back and light underside, which may help a swimmer blend in
- crèche
- a group of growing chicks found in some species
- fledging
- the move toward independent life at sea after growing suitable feathers
- food web
- the connected feeding relationships among living things
- guano
- bird droppings; stains help researchers locate emperor colonies
- incubation
- keeping an egg warm while the chick inside develops
- insulation
- a barrier that slows heat loss
- land-fast ice
- sea ice attached to the coast
- molt
- the replacement of old feathers with new ones
- myoglobin
- a substance that binds oxygen in muscle, including the muscles of emperor penguins
- preening
- using the bill to clean and rearrange feathers and spread oil
Penguins, Unfolded: The Science of a Seabird's Life
Fold 6 · Deep Dive · Ages 12+
What it is for
Fold 6 is connected popular science for readers of twelve and up and for adults. It retains species-specific evidence and uncertainty, with no child-guide dialogue. Notes and references identify the research behind the factual passages; the diagrams explain structures and processes without inventing measurements. For a shorter route through the same six subjects, try Fold 5, Penguin: A Field Guide.
Talk about it
Start from a chapter:
- A bird between places
- How a wing becomes a flipper
- A dive is an oxygen budget
- Keeping a workable temperature
- An egg through winter
- Finding and feeding a chick
Words
This fold has no glossary or word list.