Knowledge & Navigation

The QR Code: A Pattern That Reads the World

⏱ 45 minutes 🎓 Primary & Secondary 📚 mathematics, history, science, ethics, citizenship

Core question How did a pattern of black and white squares, invented in 1994 to track car parts, become one of the most widely used pieces of information technology in the world — and what does its design teach us about good engineering?

A QR code. The three large square patterns in the corners are finder patterns — they let a camera find the code from any angle. Invented in 1994 in Japan by Masahiro Hara of Denso Wave, the QR code is now used billions of times a day worldwide. Photo: Κωνσταντίνος13 / Wikimedia Commons / CC BY-SA 3.0

Introduction

Look at a QR code. To human eyes, it looks like a random pattern of black and white squares — perhaps a piece of modern art, perhaps decoration. It is neither. It is information. Each square is a piece of data. Together the squares spell out a website address, a payment code, a contact card, a piece of text, or anything else that can be written in a string of characters. The pattern was designed in Japan in 1994 by an engineer called Masahiro Hara. He worked for a small team at Denso Wave, a subsidiary of the major Japanese auto parts company Denso. The team had been asked to design a better way to track car parts on factory production lines. Traditional barcodes — the lines you see on supermarket products — were not enough. They could only hold about 20 alphanumeric characters. They had to be aligned correctly with the scanner. They became unreadable when smudged. Hara's team needed something better. The solution Hara designed was inspired partly by the Japanese board game Go. In Go, players place black and white stones on a grid. Hara realised that a two-dimensional grid of black and white squares could hold much more information than a one-dimensional line of bars. He added three large square 'finder patterns' in three corners — these let a camera find the code from any angle, even upside down. He used Reed-Solomon error correction so that even if part of the code was damaged, the rest could still be read. The result was the QR code: 'Quick Response code', because it was designed to be read very fast. The first QR code was used in 1994 to track car parts. By 2002, QR codes were spreading across Japanese industry and into general public use through camera phones. By the 2010s, QR codes were ubiquitous in China, where companies like Alipay and WeChat Pay built their entire payment systems around them. By 2025, over 2 billion QR-based payments were happening in China every day. Then came COVID-19. From 2020, QR codes spread worldwide as the standard way to access restaurant menus without touching paper, to register for vaccination passes, to check into venues for contact tracing, to make contactless payments. The QR code, once a niche industrial tool, became part of daily life almost everywhere. One key decision made it all possible. Denso Wave kept the patent on the QR code but declared that they would not enforce it. Anyone could use QR codes for free. The design was open to the world. This lesson asks how a small Japanese engineering team designed a pattern that the world adopted, and what it teaches us about good design and open technology.

The object

Origin: Invented in Japan by Masahiro Hara and his small team at Denso Wave (a subsidiary of Denso Corporation, a major auto parts company) in 1994. Designed originally to track car parts on factory production lines.
Period: In use since 1994. Adopted across Japanese industry by the late 1990s. Spread to general public use through camera phones from the 2000s. Now used billions of times daily worldwide.
Made of: A pattern of black and white squares (or other contrasting colours) arranged in a square grid. Standard sizes range from 21x21 modules to 177x177 modules. The pattern includes finder patterns (the three large corner squares), alignment patterns, timing patterns, format information, and the actual data — all encoded in black-and-white squares.
Size: QR codes can be any physical size — from a few millimetres for medical labels to several metres for billboards. The code itself is information, not a fixed-size object. The same pattern works at any size as long as a camera can resolve the squares.
Number of objects: Billions of QR codes are scanned every day worldwide. Over 2 billion daily QR-based payments are made in China alone. There is no single 'object' to count — QR codes exist on packages, restaurant menus, museum exhibits, train tickets, payment terminals, business cards, posters, screen displays, vaccination certificates, and many more places.
Where it is now: Everywhere. On product packaging, shop windows, restaurant tables, museum exhibits, vaccination certificates, payment terminals, advertising posters, and screens worldwide. Especially common in China, Japan, and other Asian countries; spreading rapidly elsewhere since the COVID-19 pandemic of 2020-2022.

Before you teach this — reflect

Questions for you

The QR code is a piece of engineering most students see every day but probably do not understand. How will you teach the technology clearly without getting too technical?
The QR code is a Japanese invention that has become a global standard. How will you credit Japanese innovation honestly?
QR codes have privacy and security concerns. How will you teach the benefits and the risks fairly?

Common student difficulties — tick any you have noticed

My students may not know that QR codes were invented in Japan in 1994 by Masahiro Hara at Denso Wave.
My students may not know that the QR code was designed for tracking car parts and only later became a public technology.
My students may not know that the design was inspired by the Japanese board game Go.
My students may not know that Denso Wave kept the patent but did not enforce it, allowing free worldwide use.
My students may not know that QR codes use Reed-Solomon error correction so they can still be read when partly damaged.
My students may not know that COVID-19 was a major factor in the worldwide spread of QR codes from 2020 onwards.

Discovery sequence

In 1992, an engineer at Denso (then a subsidiary of Toyota, now a separate auto-parts giant) was given a problem. Workers on the factory floor were complaining. They were using barcodes to track car parts, but barcodes were limited. Each barcode could hold only about 20 letters or numbers. The barcodes had to be aligned correctly with the scanner. They got dirty in factory conditions and became unreadable. The engineer was Masahiro Hara. He had a small team — just two people. They were asked to design a better code that could hold more information, including Japanese kanji and kana characters as well as alphanumeric ones. Hara thought about the problem differently. Existing two-dimensional codes packed in as much information as possible, but they were hard to read fast. Hara wanted speed. He decided to design a code that could be read more than 10 times faster than existing barcodes. During lunch breaks, Hara played Go — the ancient Japanese board game where players place black and white stones on a 19x19 grid. He noticed something. The black and white stones on the Go board were arranged in patterns that the brain could recognise quickly. Could a two-dimensional code work the same way? Why might a board game help solve an engineering problem?

Points to consider (for the teacher)

Because pattern recognition is a deep human ability that engineers can borrow. Hara saw that the brain processes the Go board fast — players see entire positions at a glance. The same principle could work for a barcode. The problem was making sure the code's orientation was clear. If a 2D code could be scanned from any angle, the scanner had to find the code first, then read it. Hara solved this with three large square 'finder patterns' in three corners of the code. The fourth corner has a smaller alignment pattern. Together, these tell the scanner exactly where the code is and which way up. The trick is that the finder patterns use the ratio 1:1:3:1:1 — meaning the proportions of black and white in the pattern are 1 unit black, 1 unit white, 3 units black, 1 unit white, 1 unit black. Hara discovered this ratio by analysing thousands of printed images, looking for the least-common ratio. By choosing a ratio that almost never appears in printed materials, the scanner could find the QR code instantly without confusion. Students should see that 'engineering inspiration' often comes from outside engineering. Hara's QR code came partly from Go. Many other inventions have similar stories — Velcro came from a man noticing burrs on his dog's fur, the Wright brothers' aeroplane came partly from watching birds. End the discovery by saying that the best engineers are good observers as well as good thinkers.

A QR code does not just hold information. It holds information that can be partly damaged and still readable. This is one of the most important features of the design. The key is something called Reed-Solomon error correction. This is a piece of mathematics developed in 1960 by two American engineers, Irving Reed and Gustave Solomon. It works like this: if you want to send a message that might get partly lost or corrupted, you add extra 'check' data to the message. The check data is calculated from the message itself using a specific mathematical formula. If part of the message gets damaged, the receiver can use the check data to reconstruct the lost parts. QR codes use Reed-Solomon error correction at four different levels: L (low, about 7% of the code can be damaged), M (medium, 15%), Q (quartile, 25%), and H (high, 30%). At the H level, you can scribble on a third of the QR code with a black pen and it will still scan correctly. This is why QR codes work in real-world conditions. A code on a factory part might get covered with grease. A code on a poster might fade in sunlight. A code on a restaurant menu might get coffee splashed on it. Through all of this, the code still scans, because the error correction protects the data. The Reed-Solomon approach was already being used in CDs, DVDs, satellite communications, and many other technologies before QR codes used it. Hara borrowed an existing solution to a related problem. He did not invent error correction. He used it cleverly. Why might 'borrowing existing solutions' be a good engineering principle?

Points to consider (for the teacher)

Because most engineering problems have already been partly solved by someone, somewhere, in some other field. The good engineer knows how to find existing solutions and combine them in new ways. Hara borrowed Reed-Solomon error correction (American mathematics, 1960). He borrowed the principle of two-dimensional grids (existing in many cultures). He borrowed the visual logic of Go (Japanese tradition). He combined these with his own insight about the 1:1:3:1:1 finder pattern ratio. The result was new, but most of the components were old. The deeper point is that 'invention' is often recombination. The car combined the wheel (very old), the internal combustion engine (1860s), the rubber tyre (1888), and many other existing parts. The smartphone combined the mobile phone, the camera, the GPS, the touchscreen, the music player, and many other things. Most great inventions are syntheses. Students should see that 'creativity' includes finding existing tools and using them in new combinations. Hara was creative in this way. The QR code is a synthesis. End the discovery here.

Denso Wave finished developing the QR code in 1994. The team had spent eighteen months on it. Hara had built a code that could store about 7,000 characters and could be read more than ten times faster than existing barcodes. Then came a critical decision. Denso Wave applied for and received the patent on the QR code. Patents normally let the owner charge other companies for using the technology. Denso could have made huge amounts of money this way. Denso decided not to. The company declared that it would not enforce its patent rights. Anyone could use QR codes for free. This decision was made from the very beginning, honoring the developers' desire that the code should be used by as many people as possible. The decision was unusual. Most companies enforce their patents aggressively. But Denso had calculated something else. If the QR code became a free public standard, used by everyone, the company name would be associated with it. The advertising value of being known as the inventor of QR codes was huge. Denso Wave did add a polite request that companies using QR codes mention 'QR Code is a registered trademark of DENSO WAVE INCORPORATED' alongside the codes — which they often did, providing free advertising. The strategy worked spectacularly. By 2002, QR codes were spreading across Japanese industry and into general public use. By the 2010s, they were everywhere in China. By the 2020s, they were everywhere in the world. The QR code became the dominant 2D barcode standard, used by everyone, while Denso Wave became internationally known. Why might giving away a technology be smarter than charging for it?

Points to consider (for the teacher)

Because adoption beats royalties. A patented technology that nobody uses earns nothing. A free technology that everyone uses creates the user base, the standards, the supply chains, and the brand recognition. Denso Wave still earns money from QR-related products — barcode readers, software, services. They just do not charge for the basic code itself. Compare with other examples: Linux (the free operating system that runs most servers, smartphones, and many other devices) is open-source, but companies like Red Hat make billions of dollars supporting it. Wikipedia is free, but it has become the world's largest reference work. The HTTP protocol that runs the web is free, allowing the entire web economy to exist. M-Pesa (the Kenyan mobile money service in another lesson in this collection) was given regulatory protection that allowed it to grow. The pattern is clear: in many cases, free or open technology spreads faster and ultimately benefits the originator more than charged technology. Students should see that 'who owns the technology?' is sometimes less important than 'how can it spread?'. Denso Wave understood this in 1994. The result is that the QR code is now part of daily life worldwide, and Denso Wave is famous for inventing it. End the discovery here.

For the first 25 years of its life, the QR code was useful but not universal. It spread quickly in Japan after 2002 (when Japanese mobile phones started including QR readers). It spread quickly in China after 2011 (when Alipay and WeChat Pay built their payment systems around it). But in the United States, Europe, and many other places, QR codes were used here and there but never became part of daily life. Then came COVID-19. From early 2020, restaurants, shops, museums, and venues worldwide needed contactless ways to do everything. Paper menus were potential disease carriers. Cash transactions involved physical contact. Sign-in registers needed to be replaced. The QR code was the obvious solution. It had been there all along. Now everyone needed it. Restaurants put QR codes on every table — scan to see the menu. Pubs and shops put QR codes at the door — scan to register for contact tracing. Vaccine providers issued QR codes as vaccination certificates. Train tickets, plane tickets, event tickets — all moved to QR codes. The technology that had been around for 26 years suddenly became universal. In 2020, even the iPhone — which had not natively supported QR codes when it launched in 2007 — gained native QR code scanning in iOS 11 and improved support afterwards. Android did the same. Suddenly, every smartphone in the world could scan QR codes directly with the camera app, no extra app needed. By 2024, daily QR code scans were estimated in the billions worldwide. China leads with over 2 billion QR-based payments per day, but other countries are catching up. The QR code is now essential infrastructure of daily life. What lessons does this teach us?

Points to consider (for the teacher)

Several at once. First, that good technology can wait for its moment. The QR code was technically excellent in 1994 but did not become globally universal until 2020. Twenty-six years is a long time to wait, but the design was good enough that when the moment came, it was ready. Second, that crises drive adoption. COVID-19 was a tragedy, but it pushed many beneficial changes that had been resisted for years — remote work, contactless payment, online education, telemedicine. The QR code's universal adoption was one of these. Third, that infrastructure becomes invisible when it works. Most people now use QR codes daily without thinking about them. The Japanese engineer Masahiro Hara, who designed them, is mostly unknown outside Japan. Good infrastructure becomes background. Fourth, that openness multiplies value. Because Denso did not enforce the patent, the QR code could become a global standard. If they had enforced it, COVID would have spread differently — perhaps governments would have had to use less efficient alternatives. The free availability mattered. Students should see that the QR code is a piece of infrastructure they probably use daily. Almost no one knows the inventor's name. The pattern is part of how the world works now. End the discovery here. The next QR code is being scanned right now. The simplest pattern is doing a complicated job. Now you know what is happening.

What this object teaches

A QR code (Quick Response code) is a two-dimensional matrix barcode that can hold much more information than traditional one-dimensional barcodes. It was invented in 1994 in Japan by Masahiro Hara and his team at Denso Wave, a subsidiary of the major Japanese auto-parts company Denso. The original purpose was to track car parts on factory production lines. The design was inspired partly by the Japanese board game Go. The three large square 'finder patterns' in three corners use the ratio 1:1:3:1:1 — a ratio chosen because it almost never appears in printed materials, allowing the code to be found instantly. Reed-Solomon error correction means QR codes can be partly damaged and still readable. Denso Wave kept the patent but declared they would not enforce it — anyone could use QR codes for free. This decision allowed worldwide adoption. By 2002 QR codes were spreading across Japanese industry. By the 2010s they were universal in China, where Alipay and WeChat Pay built their payment systems around them. The COVID-19 pandemic from 2020 drove worldwide adoption — restaurant menus, vaccine certificates, contactless payment, event tickets all moved to QR codes. By 2024, billions of QR codes were being scanned daily worldwide. Over 2 billion QR-based payments happen in China each day. The QR code is now essential infrastructure. Masahiro Hara, the inventor, has stated that the current widespread use was completely unexpected when the code was designed.

Date	Event	What changed
1992	Denso Wave begins QR code project	Masahiro Hara and his team start designing a 2D barcode for car parts tracking
1994	QR code launched	Eighteen months of development complete; the design includes finder patterns and Reed-Solomon error correction
Mid-1990s	Denso Wave declines to enforce patents	QR codes can be used by anyone for free; foundation laid for worldwide adoption
2002	Japanese camera phones add QR readers	General public use begins; QR codes spread across Japanese society
2011-2014	Alipay and WeChat Pay launch QR-based payments	China adopts QR codes as the dominant payment method
2017	iOS 11 adds native QR code scanning	Apple finally supports QR codes directly; Android follows; every smartphone can now scan
2020-2022	COVID-19 drives worldwide adoption	QR codes become essential for contactless menus, vaccine certificates, and many other uses
Today	Universal infrastructure	Billions of QR codes scanned daily worldwide; over 2 billion QR-based payments per day in China alone

Key words

QR code

Quick Response code. A two-dimensional matrix barcode invented in 1994 by Masahiro Hara at Denso Wave in Japan. Holds much more information than one-dimensional barcodes. Can be scanned by smartphone cameras and other imaging devices.

Example: A standard QR code holds up to about 7,000 numerical characters or 4,000 alphanumeric characters. It can also encode Japanese kanji characters, Arabic letters, Chinese characters, or any other Unicode text.

Masahiro Hara

Japanese engineer (born 8 August) who led the team that invented the QR code in 1994. Began work at Denso Corporation in 1980. Currently chief engineer at Denso Wave. Awarded the European Inventor Award in 2014 for his QR code work.

Example: Hara has stated that the current widespread use of QR codes was completely unexpected. He has said: 'I felt that I had developed something great, and predicted that it would be widely used in the industry. But it was widely used by general users, which I did not expect.' World QR Code Day is celebrated every August 8 — Hara's birthday.

Finder pattern

The three large square patterns in three corners of every QR code. They allow a scanner to find the code from any angle. The pattern uses the ratio 1:1:3:1:1 of black and white widths, a ratio chosen because it almost never appears in printed materials.

Example: The finder pattern is the most distinctive feature of QR codes. The three large corner squares are why the code is so easy to find — even when partly hidden, photographed at an angle, or printed on a curved surface, the scanner can lock onto the finder patterns and orient correctly.

Reed-Solomon error correction

A mathematical method for adding redundant data to a message so that errors can be corrected. Invented by Irving Reed and Gustave Solomon in 1960. Used in QR codes (and in CDs, DVDs, hard drives, satellite communications, and many other technologies).

Example: QR codes have four error correction levels: L (about 7% can be damaged), M (15%), Q (25%), H (30%). At the H level, you can scribble on a third of the QR code with a marker and it will still scan correctly.

Denso Wave

The Japanese company that invented the QR code. A subsidiary of Denso Corporation, a major automobile parts manufacturer. Headquartered in Agui, Aichi Prefecture, Japan. Now also makes barcode readers, robots, and industrial automation equipment.

Example: Denso Wave kept the patent on the QR code but declared it would not enforce its rights. This decision allowed the QR code to become a worldwide free standard. Denso Wave still profits from selling related products — readers, software, services.

Alipay and WeChat Pay

The two dominant Chinese mobile payment systems, both built around QR codes. Alipay (launched 2003) is run by Alibaba; WeChat Pay (launched 2013) is run by Tencent. Together they handle billions of transactions per day.

Example: In urban China, QR-based payment is so universal that some shops do not accept cash. Beggars sometimes carry QR codes for digital donations. The Chinese government has had to issue rules requiring shops to accept cash to ensure that older people without smartphones are not excluded.

Use this in other subjects

Mathematics: A QR code is a binary system — each cell is either black (1) or white (0). A standard 21x21 small QR code has 441 cells. After deducting finder patterns and metadata, perhaps 130 cells hold actual data — enough for about 25 alphanumeric characters. Calculate: how many possible 21x21 patterns are there in total? (2^441, an astronomical number.) Use this to discuss combinatorial mathematics.
History: Build a class timeline of identification technology: handwritten labels, printed labels, magnetic strips, traditional barcodes (1974), QR codes (1994), RFID chips (2000s), biometric identification (2010s onwards). Each step increased the amount of information that could be associated with an object.
Science: A QR code is read by a camera and decoded by software. The camera detects light and dark areas; the software identifies the finder patterns, then reads the data cells, then applies error correction. Each step is a piece of pattern recognition. Discuss: how does a smartphone do this in less than a second?
Citizenship: In China, QR-based payment has become so universal that some people without smartphones (older people, the very poor) struggle to participate in daily commerce. Discuss: what are the responsibilities of a society as it moves to digital systems? How do you avoid leaving people behind?
Ethics: QR codes can be malicious — a fake code on a poster might link to a phishing site. Privacy concerns are real — apps that scan QR codes often request many permissions. Discuss: how should users protect themselves? What are the responsibilities of QR code creators? Strong answers will see this as a real ongoing question.
Art: QR codes can be styled — coloured, decorated, embedded with logos — while still scannable. The artist qargo and others have created QR code artworks. Each student designs a hypothetical QR code-themed piece on paper. Discuss: function and beauty can coexist. Many other functional objects (typography, road signs, currency) are also designed.

Common misconceptions

Wrong

QR codes are an American invention.

Right

QR codes were invented in Japan in 1994 by Masahiro Hara at Denso Wave. The Reed-Solomon error correction they use was invented by Americans (Reed and Solomon, 1960), but the QR code itself is a Japanese invention.

Why

Crediting Japanese innovation matters; many technologies attributed to America were in fact invented elsewhere.

Wrong

QR codes contain only website links.

Right

QR codes can hold any text — phone numbers, contact cards, payment instructions, Wi-Fi network details, plain text, mathematical formulas, anything that can be written. They are containers for information of any kind.

Why

Restricting QR codes to URLs ignores their wider use, especially in payments and contact tracing.

Wrong

QR codes are completely safe.

Right

QR codes can be malicious. Fake codes can link to phishing sites, malware downloads, or fraudulent payment requests. The QR code itself is morally neutral, but what it contains can be dangerous. Users should be careful about scanning codes from untrusted sources.

Why

Treating any technology as 'completely safe' ignores real risks.

Wrong

The QR code became universal because it was the best technology available.

Right

The QR code became universal partly because of its design but also because Denso Wave gave it away free, because COVID-19 created sudden demand, because smartphones became universal, and because Chinese payment platforms standardised on it. The technology was good; the timing and openness mattered too.

Why

Treating adoption as purely about technical merit ignores the role of business decisions, social events, and timing.

Teaching this with care

Treat the QR code as a serious example of Japanese engineering. Use 'QR code' (with capital QR) consistently — it stands for Quick Response. Pronounce 'QR' as 'cue-ARR'. Pronounce 'Masahiro Hara' as 'mah-sah-HEE-roh HAH-rah'. Pronounce 'Denso Wave' as 'DEN-so WAVE'. Pronounce 'Reed-Solomon' as 'REED-SO-loh-mon'. Pronounce 'Alipay' as 'AH-lee-pay'; 'WeChat Pay' as 'WEE-chat pay'. Be careful to credit Japanese engineering properly. The QR code is one of many recent Japanese inventions that have become global standards (others include the JPEG image format, the lithium-ion battery, the GPS receiver chip used in early consumer devices). Avoid framing the story as 'rich country technology spreading to poor countries' — it is more accurately 'Japanese technology becoming a global standard via Asian adoption first, then global'. Be balanced about the privacy and security risks. QR codes have benefits (convenience, accessibility, error tolerance) and real risks (phishing, fraud, surveillance). Mention both. Be aware that some students may have had bad experiences with QR codes — phishing, lost vaccine certificates, scams. Acknowledge this without dwelling on it. Be respectful of how QR codes have changed society in different countries. In China, QR-based payment has been transformative but has also raised real concerns about exclusion of people without smartphones. In Japan, QR codes have been used widely for over 20 years with relatively few problems. In the West, mass adoption only happened with COVID-19. Each context is different. Avoid the lazy 'tech is amazing' framing. Good engineering is real, but technology by itself does not solve problems — it shapes them. The QR code's worldwide spread depended on COVID-19, which was a tragedy. The relationship between technology and society is complex. If you have students who use QR codes for daily life (payments, transit, identification), give them space to share. If you have students who do not, do not assume universal use. End the lesson on the present. QR codes are alive, growing, and changing. The story continues.

Check what students have understood

Answer each question in one or two sentences. Use what you have learned about the QR code.

Where, when, and by whom was the QR code invented?

In Japan in 1994, by Masahiro Hara and his small team at Denso Wave, a subsidiary of Denso Corporation. The original purpose was to track car parts on factory production lines.

Marking note: Award full marks for any answer that names Japan, gives the date 1994, and names Hara or Denso Wave.
How does a QR code work?

It is a pattern of black and white squares in a grid. Three large 'finder patterns' in three corners let a camera find the code from any angle. The rest of the squares hold the actual data, encoded as binary information. Reed-Solomon error correction protects the data — even if part of the code is damaged, the rest can be read. A scanner reads the code in less than a second.

Marking note: Strong answers will mention the finder patterns, the binary squares, and the error correction. Two of these is enough for partial credit.
Why did Denso Wave's decision not to enforce the patent matter?

It allowed anyone to use QR codes for free. This led to worldwide adoption — first across Japanese industry, then globally through smartphones and Chinese payment systems. If Denso Wave had charged for the patent, the QR code would probably never have become universal. Denso Wave still profits from selling related products like readers and software.

Marking note: Award full marks for any answer that explains the link between free use and worldwide adoption.
What was the role of COVID-19 in spreading QR codes?

From 2020, the pandemic created sudden demand for contactless ways to do everything — restaurant menus, vaccine certificates, sign-in registers, payments. QR codes were the obvious solution. They had been around since 1994 but only became universal worldwide because of the pandemic. Smartphones already supported them, so adoption was very fast.

Marking note: Strong answers will mention contactless interaction, specific examples (menus, certificates), and the rapid worldwide adoption.
What does the QR code teach us about good engineering?

Good design solves real problems (Hara solved the slow-reading barcode problem). Good design borrows existing solutions (Hara used Reed-Solomon error correction from 1960). Good design takes inspiration from outside its own field (the Go board game inspired the 1:1:3:1:1 ratio). Good design that is given away spreads further than design that is charged for.

Marking note: Award full marks for any answer that draws at least two engineering lessons from the story.

Discuss together

These questions have no single right answer. Talk in pairs or small groups, then share your ideas with the class.

Denso Wave decided not to charge for the QR code, even though they had the patent. Was this a good decision?

Push students to think about the strategy. Arguments for: the QR code became a global standard and Denso Wave became famous; the company still profits from related products; the world benefits from a free standard. Arguments against (or for nuance): Denso Wave probably could have made enormous direct profit from licensing fees; some other companies (Alipay, WeChat Pay) made huge profits from QR code-based businesses without paying anything to Denso. The deeper point is that 'open' often beats 'closed' for spreading a standard. Linux, the web, and many other open technologies have shown the same pattern. Strong answers will see that the decision was strategic — Denso traded direct revenue for indirect benefits. End by asking what other free or open technologies have changed students' lives.
In China, QR codes are so universal that some people without smartphones cannot easily participate in daily commerce. What are the responsibilities of a society as it moves to digital systems?

This is a question about inclusion. Students may suggest: maintain alternative options (cash, paper); subsidise smartphones for the elderly or poor; design systems for low-tech accessibility; teach digital skills. The deeper point is that 'progress' that excludes some people is not really progress. The Chinese government has had to issue rules requiring shops to accept cash because of complaints from older people. Other countries face similar issues — automatic ticket machines, online banking, digital health systems all create exclusion if not carefully designed. Strong answers will see that inclusive design is a real responsibility, not optional. End by asking what students notice about who is excluded by digital systems in their own community.
The QR code was inspired partly by the Japanese board game Go. What other inventions have come from unexpected sources?

This is a creative question. Students may suggest: Velcro (from burrs on a dog), the Wright brothers' aeroplane (from watching birds), the chocolate chip cookie (from breaking up a chocolate bar), the microwave (from a melted chocolate bar in a radar engineer's pocket), penicillin (from a contaminated petri dish). The deeper point is that good ideas often come from observation in unexpected places. The best engineers and scientists are often good observers, not just good thinkers. Hara playing Go was not 'wasted time' — it was the moment he saw a pattern he could use. End by asking what students have learned from unexpected sources, and how they could be more open to inspiration outside their direct study.

Teaching sequence

THE HOOK (5 min)

Without saying anything about the lesson, hold up (or describe) a QR code. Ask: 'What is this, and where was it invented?' Take guesses. Then say: 'It is a QR code, invented in Japan in 1994 to track car parts. Today billions are scanned every day worldwide. We are going to find out about it.'
INTRODUCE THE OBJECT (10 min)

Describe the QR code: a pattern of black and white squares; three large finder patterns in the corners; data in the rest; error correction so it works when partly damaged. Pause and ask: 'How does a smartphone read a pattern like this in less than a second?' Listen to answers — they will lead to the ideas of pattern recognition and software.
HARA AND THE GO BOARD (15 min)

Tell the story: Masahiro Hara at Denso Wave, problem with barcodes, eighteen months of development, inspiration from Go, the 1:1:3:1:1 ratio. Discuss: how does a board game inspire a barcode? Other invention stories — Velcro from burrs, the aeroplane from birds. Then explain: Denso Wave kept the patent but did not enforce it. Discuss: why give away a technology?
THE COVID MOMENT (10 min)

Tell the worldwide adoption story: Japan 2002 (camera phones), China 2011-2014 (Alipay/WeChat Pay), iPhone 2017 (native scanning), COVID-19 2020 (universal adoption). The QR code waited 26 years for its global moment. Discuss: how does timing matter for technology?
CLOSING (5 min)

Ask: 'What does the QR code teach us about engineering, openness, and the spread of useful technology?' Take a few honest answers. End by saying: 'Right now, somewhere in the world, billions of QR codes are being scanned. Almost no one knows the name Masahiro Hara. The pattern in the corner of a restaurant menu, the box of cereal, the vaccine certificate, came from a small team in Japan in 1994. They gave it to the world for free. Now it runs through your daily life. Now you know.'

Classroom materials

Decode the Pattern

Instructions: Show students the structure of a QR code on the board: three large finder patterns in the corners, smaller alignment pattern in the fourth, timing patterns along edges, format information near the finders, data filling the rest. Each student draws their own version on graph paper, with at least the three finder patterns. Discuss: every QR code has the same basic structure. The data changes, but the framing pattern is fixed.

Example: In Mr Sato's class, students drew QR-code-like patterns on graph paper with the three finder squares. The teacher said: 'You have just designed the framework that every QR code in the world uses. The three finder squares mean a camera can find the code from any angle. The 1:1:3:1:1 ratio means it cannot be confused with random patterns. Hara's design was beautifully simple. Once you see how it works, it is hard to imagine a better solution.'

Find a QR Code

Instructions: For homework, students find five QR codes in their daily life and note where they are. Examples: on shop windows, on cereal boxes, on bus stops, on advertisements, on vaccination cards. The next class, students share where they found codes and what they were for. Discuss: QR codes are everywhere once you start looking.

Example: In Mrs Li's class, students returned with examples from supermarkets, cafés, train stations, museums, and even pet adoption notices. The teacher said: 'You have just discovered how saturated daily life is with QR codes. Each one is doing a small job. The codes are designed to be invisible — present but not obtrusive. The technology has become infrastructure, like electricity or running water. Most people use it every day without thinking about it. The Japanese team that invented it would be amazed.'

Inspiration From Anywhere

Instructions: In small groups, students discuss: 'What hobby, game, or activity could inspire a new invention?' Each group picks one (chess, football, knitting, cooking, music) and brainstorms what engineering or design ideas could come from it. Each group shares one idea. Discuss: Hara found inspiration in Go. Many inventors find inspiration outside their direct field.

Example: In one class, students suggested: knitting could inspire patterns for textile-based circuits; football could inspire team-based AI; music could inspire algorithms for emotional recognition; cooking could inspire chemistry teaching tools. The teacher said: 'You have just done what Hara did. You have looked at activities you know well and seen possible technical applications. The best engineers do this all the time. Knowledge from one field crosses into another. Stay curious about what you do outside school. Your own hobbies might be the source of your future ideas.'

Where to go next

Try a lesson on the cowrie shell for another object that became a global standard.
Try a lesson on M-Pesa for another contemporary innovation that started in one country and spread globally.
Try a lesson on the silk road scale for another piece of trust-and-information technology.
Connect this lesson to mathematics class with a longer project on error correction codes. Reed-Solomon mathematics is accessible to advanced students.
Connect this lesson to design class with a longer project on inclusive design. The Chinese cash-acceptance issue is a real example.
Connect this lesson to citizenship class with a longer discussion of digital infrastructure and exclusion. QR codes are one example of many.

Key takeaways

The QR code (Quick Response code) is a two-dimensional barcode invented in 1994 in Japan by Masahiro Hara and his team at Denso Wave. The original purpose was to track car parts on factory production lines.
The design includes three large finder patterns in three corners (using the 1:1:3:1:1 ratio that almost never appears in printed materials), data cells filling the rest, and Reed-Solomon error correction that allows the code to be partly damaged but still readable.
Denso Wave kept the patent but declared it would not enforce it. This decision allowed anyone to use QR codes for free and was crucial for worldwide adoption.
QR codes spread first through Japanese industry (1990s), then through Japanese mobile phones (2002 onwards), then through Chinese payment systems (2010s onwards) like Alipay and WeChat Pay.
COVID-19 from 2020 drove worldwide adoption — restaurant menus, vaccine certificates, contactless payments, sign-in registers all moved to QR codes. The technology had been around for 26 years but became universal only with the pandemic.
Today, billions of QR codes are scanned daily worldwide. Over 2 billion QR-based payments happen in China each day. The QR code is now essential infrastructure of daily life, mostly invisible because it works.

Sources

History of the QR Code — Denso Wave Incorporated (2024) [institution]
QR Code Inventor Masahiro Hara — Japan Patent Office (2014) [institution]
How the QR Code Conquered the World — BBC News (2022) [news]
Polynomial Codes Over Certain Finite Fields — Irving Reed and Gustave Solomon (1960) [academic]
The Open Source Strategy of Denso Wave — Harvard Business Review (2021) [news]

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