Extensive reading for children: a parent's guide

Published October 5, 2026 · Last updated October 5, 2026 · By Tom, founder of Mukashi

Extensive reading (tadoku in Japanese) means reading lots of easy English books for pleasure, without a dictionary. Unlike intensive reading, which translates and analyzes a text line by line, it builds English through quantity and enjoyment. Children start with short picture books that have pictures and sound. A public library's tadoku shelf makes it free.

Extensive vs intensive reading

At school, children mostly learn intensive reading. They read short texts carefully, with a dictionary and grammar. Extensive reading is the opposite: easy books, read smoothly, and lots of them.

The guide is the share of words your child doesn't know. The guide published by the Extensive Reading Foundation (ERF), an international nonprofit, says that readers who know about 98% of the words on a page read quickly and enjoyably, and that below 90% reading becomes frustrating (2011). 98% means about one unknown word in 50.

Neither one is "right". They do different jobs.

Who came up with the three principles of tadoku?

The "three principles of tadoku" were published by Kunihide Sakai, who taught extensive reading classes at the University of Electro-Communications, in his 2002 book Kaidoku Hyakuman-go! Paperback e no Michi. The SSS Extensive Reading Society and the NPO Tadoku Supporters have spread them since.

1. Don't use a dictionary.
2. Skip what you don't understand.
3. Stop when it gets boring (or when a book doesn't suit you).

The third has several wordings, as Sakai himself writes. What matters is the idea: don't read a book you can't enjoy. Day and Bamford's "top ten principles for teaching extensive reading" (2002), widely cited outside Japan, point the same way: "The reading material is easy." "Learners choose what they want to read." "Learners read as much as possible."

Why does extensive reading work?

• Lots of English you understand. The linguist Stephen Krashen gathers the research and argues that free voluntary reading, reading for pleasure, builds language ability (2004).
• Meeting the same words again and again. Paul Nation calculated (2014) that meeting the 1,001st to 2,000th most frequent words at least 12 times on average takes just under 200,000 words of text.
• Research with children, too. In Fiji, primary school children who read many English storybooks progressed in reading and listening comprehension at about twice the rate of children who didn't (Elley & Mangubhai, 1983).
• Across many studies. A 2025 meta-analysis of 73 studies found small to medium positive effects in every area it looked at, including reading comprehension, vocabulary, writing, speaking and motivation (Sangers and colleagues).

But only 7 of the 82 programs in that analysis were in primary schools. Most of the research is with university students, and extensive reading with children is still a thinly researched area.

When to start: a guide by age

Ages 4 to 6: listen and enjoy, together

Your child doesn't need to read alone. This is time for listening to a read-aloud or audio, looking at the pictures and enjoying the story. Start with wordless picture books, or books with one word on a page. Wanting the same book again and again counts as extensive reading too. There is almost no research on extensive reading with preschoolers, so the aim is a feeling rather than a result: English books are fun.

Ages 6 to 12: from audio toward reading alone

Elementary school English covers about 600 to 700 words in all, from Foreign Language Activities in grades 3 and 4 to Foreign Language in grades 5 and 6 (Course of Study, 2017). Extensive reading starts with books much easier than the textbook. At first, your child listens to audio and follows the words with their eyes. As more books feel easy, they read on their own.

Levels: YL and Oxford Reading Tree stages

Japanese tadoku often uses YL (yomiyasusa level, "ease-of-reading level"), started in 2003 by Akio Furukawa of the SSS Extensive Reading Society. It has 100 steps from 0.0 to 9.9. YL 0.0 is a book you can read without knowing any English, and YL 3.0 is a children's book of about 10,000 words.

Oxford Reading Tree (ORT), a picture-book series written for children learning to read in the UK, is a classic first step in tadoku. These are the YLs and words per book that SSS published (2014). Newer editions call the stages "levels".

Which Eiken grade is each ORT stage?

An exact table isn't possible. The publisher, Oxford University Press, explains that ORT was written for children's literacy in the UK and isn't divided by grammar level, so it doesn't correspond to Japanese tests. The Eiken Foundation describes Grade 5 as about early junior high school level, and Grade 4 as mid junior high school level. When choosing a book, "about one unknown word in 50" is a better guide than a grade.

How much should they read?

The ERF guide says schools typically ask students to read about one book a week or more. SSS suggests reading the first 100,000 words as 20,000 words at YL 0 and 80,000 words at YL 1. With 100-word books, 20,000 words is 200 books, counting rereads. On the other hand, the NPO Tadoku Supporters doesn't recommend goals like "X words this year". For children, reading a little every day matters more than the word count.

Common mistakes

1. Starting too hard. Books matched to school year or Eiken grade are usually too hard.
2. Asking "what does this mean?" It turns reading into a translation test, and the fun goes.
3. Making them finish. If a book doesn't suit them, stop and pick another.
4. Moving up too fast. SSS writes that when readers move up too quickly, most of them stop reading.
5. Buying a whole set first. Use the library to find a series your child loves.

Start free at the library

The cheapest way into extensive reading is the public library. Some libraries, like the Tokyo Metropolitan Library with its English tadoku shelf, keep series such as ORT together.

Not every library does. In a 2024 national survey by the NPO Tadoku Supporters, 119 of the 571 public libraries that answered (21%) had an English tadoku corner, and about 30% held ORT. More corners have opened since 2015. Search your library's catalog for "Oxford Reading Tree", and if it isn't there, ask whether they can get it in.

Where does an app fit?

A library gives you the fun of choosing and the feel of paper. Sound is where it struggles. For a parent who isn't confident reading English aloud, daily read-alouds can be hard to keep up. An app puts books with audio at home, every day. A library will always have more books, though. One analysis found larger effects in studies that used web-based stories (Jeon & Day, 2016), but the studies differed in many ways, so it doesn't show that screens are better. Using the library and an app together is the realistic answer.

About Mukashi

Mukashi is a story-based English extensive-reading app. Children read leveled English stories while they travel illustrated worlds with Hoshi, a small star spirit far from home. It is made for elementary-school children (6 to 12), and for children from age 4 reading with a parent.

• The stories are in English only. Mukashi is not a bilingual book series with Japanese translations. Pictures and audio carry the meaning. Everything written for parents is also in Japanese.
• Every book has audio, and the words light up as they are read.
• Today's books cover Eiken Grade 5. Every child starts at Eiken 5 and travels, world by world, toward Eiken Grade 2.
• For complete beginners there is the Schoolhouse, with phonics and forty first books. It is included in every plan.
• ¥1,980 a month, tax included. ¥1,480 a month, tax included, for each sibling.

Here is where Mukashi differs from tadoku. Every book ends with a comprehension quiz. Books in a world are read in order, as one story (books already read can be reread any time).

There are also free English coloring pages (14) and letter papers (4) to print at home.

FAQ

At what age can a child start extensive reading?

From 4 to 6, a child can start by listening to picture books with a parent. Reading alone comes once they can read a little. Watch whether your child is enjoying it, not their age.

Can we do extensive reading if I can't read English well?

Yes. With audio books or an app, you don't need to read aloud. You don't need to translate either. Your job is to look at the pictures together and enjoy them.

Which Eiken grade is each Oxford Reading Tree stage?

There is no exact match. The publisher says ORT doesn't correspond to Japanese tests. For choosing books, use YL (the ease-of-reading level) and the "about one unknown word in 50" guide.

Can extensive reading be free?

Yes. Public library books are free. But only about 1 in 5 libraries that answered a national survey had a tadoku corner. Mukashi's demo is free too: ten books, no signup.

Sources

1. ERF, Guide to Extensive Reading (2011)
2. SSS Extensive Reading Society, "Guide to SSS learning" (Akio Furukawa, revised December 8, 2023)
3. NPO Tadoku Supporters, "What are the three principles of tadoku?" (incl. Kunihide Sakai's note)
4. Day & Bamford (2002)
5. Krashen (2004)
6. Nation (2014)
7. Elley & Mangubhai (1983)
8. Sangers et al. (2025)
9. Jeon & Day (2016)
10. MEXT, Course of Study for Elementary Schools (2017)
11. Furukawa, "Yomiyasusa Levels" (SSS, March 22, 2014)
12. Oxford University Press Japan, ORT catalog FAQ (2023)
13. Eiken Foundation of Japan, grade levels
14. NPO Tadoku Supporters, "Should I record word counts?"
15. NPO Tadoku Supporters, National Survey of Tadoku Materials in Public Libraries (March 2025)
16. Tokyo Metropolitan Library, English tadoku shelf

Last updated: October 5, 2026