IELTS Academic Reading Practice Test 125

On 27 May 1843 a Scottish inventor named Alexander Bain was granted a patent for what he called a recording telegraph, a device intended to carry a picture along a wire. His design rested on a simple principle. An image was drawn on a metal plate in ink that did not conduct electricity. A stylus was then moved steadily across the surface. Wherever the stylus touched bare metal a circuit was completed and a pulse of current travelled down the line; wherever it crossed the ink, nothing happened. At the receiving end a second stylus rested on paper moistened with a chemical that darkened whenever current passed through it, so that a copy of the original was built up line by line. Bain never built a commercially successful machine, and how reliably his apparatus worked is uncertain.

In 1851 a British inventor, Frederick Bakewell, demonstrated an image telegraph at the Great Exhibition in London. His apparatus wrapped the picture around a cylinder at the sending end and the recording paper around a matching cylinder at the receiving end. Both cylinders turned while a stylus travelled slowly along them, so that the whole surface was scanned in a series of fine lines. Keeping the two cylinders turning in step proved difficult, however, and any loss of synchronisation distorted the picture beyond recognition. Bakewell's machine attracted interest and was later used in experiments, but it never entered regular service.

The first system to carry pictures for paying customers was the pantelegraph of Giovanni Caselli, an Italian physicist. It followed Bain's principle: a stylus traced a picture drawn in insulating ink on a metal plate, and a pulse of current went down the line whenever the stylus met bare metal. Caselli solved the problem of synchronisation by driving the transmitter and the receiver from a single clockwork mechanism, and his machine was dependable enough for the French telegraph administration to run a service between Paris and Lyon from the 1860s. Each image took several minutes to transmit, and skilled operators were needed to prepare the plates and keep the equipment finely adjusted.

Photographs presented a much greater challenge, because a photograph contains continuous shades of grey rather than the hard outlines of a drawing. In the early twentieth century Arthur Korn in Germany and Édouard Belin in France developed ways of scanning a print with a beam of light and turning the reflected light into an electrical signal. Belin's device, the bélinographe, was taken up by newspapers, and by the 1930s pictures were crossing the Atlantic by cable and by radio. The Associated Press began sending photographs between its offices by wire in 1935. Machines of this kind were large and costly and were operated by trained technicians, so they belonged to news organisations, police forces and a few big companies rather than to ordinary offices.

Sending a document from one office to another over an ordinary telephone line came later. Several firms demonstrated such machines in the mid-1960s, and in 1964 Xerox joined its copying technology to the telephone network in a system it called long-distance xerography. These devices were slow and temperamental by later standards, and for more than a decade the fax machine remained a specialist tool rather than standard office equipment.

Fax only became a standard technology in the 1980s. In 1980 an international committee of the telecommunications industry published a specification known as Group 3, which set out how a page should be scanned, compressed and transmitted between machines made by different manufacturers. Digital coding cut the amount of data that had to be sent, and the first Group 3 machines took about a minute to send a single page; faster modems later reduced this to a few seconds. The standard is the reason why a machine sold in one country could communicate with a machine bought in another.

Japanese manufacturers, among them Canon, Ricoh, Sharp and Brother, came to dominate the market, and it is often argued that Japan took to the fax more enthusiastically than any other country because of its writing system. A typewriter with a few dozen keys can handle English, but Japanese needs thousands of characters, and sending a page by facsimile was for a long time the simplest way to move a document across the country. By the late 1980s fax machines were common in offices throughout the industrialised world, and prices had fallen far enough for small businesses to buy them.

The retreat began in the late 1990s. Email, and later the scanned attachment, did much the same job without requiring paper at either end; by the 2010s the fax had largely disappeared from general office life.

It has not disappeared altogether. In medicine, law and property, a fax carries something that an email does not: a printed page bearing a signature, arriving on a machine in a known office, which is why hospitals and solicitors went on using it long after their other equipment had been replaced. In 2018 the health service in England announced that fax machines would be phased out by 2020, although reports suggested that several hundred were still in use afterwards. In Japan, government departments and many households continued to rely on fax for routine business well into the 2020s.

Every bridge, pipeline and aircraft wing contains flaws too small to see. A hairline crack in a metal component concentrates stress at its tip, and under repeated loading it creeps forward until the part fails. Engineers inspect large structures at fixed intervals, but a crack can grow a long way between two inspections, and reaching the inside of a sealed component may be impossible. Living organisms do not have this problem. Bone continually rebuilds itself, skin closes over a cut and trees seal wounds with resin. For a quarter of a century, materials scientists have been trying to give synthetic materials a comparable ability, so that damage is repaired where and when it occurs rather than discovered later.

Two broad strategies have emerged. The first, known as extrinsic healing, stores a healing agent inside the material and releases it when damage occurs. The second, intrinsic healing, builds the capacity for repair into the chemistry of the material itself, so that broken bonds can re-form. Each has strengths, and neither has yet displaced the other.

The modern field is usually dated to 2001, when a team at the University of Illinois led by Scott White, Nancy Sottos and Jeffrey Moore published a design for self-healing epoxy. The material contained two ingredients: microscopic capsules a few hundred micrometres across, filled with a liquid monomer, and particles of a catalyst scattered through the surrounding resin. When a crack propagated through the material it ruptured the capsules in its path, and capillary action drew the monomer into the crack, where it met the catalyst and polymerised, hardening in a few hours and bonding the two faces together. In the original experiments the repaired material recovered as much as three-quarters of its original resistance to fracture. The crack, in effect, had triggered its own repair.

Capsule systems have an obvious drawback: each capsule can be burst only once. Once the supply of monomer in the vicinity of a crack is exhausted, a second crack in the same place cannot be healed. A more ambitious approach mimics the circulatory system. In vascular materials, a network of fine channels carries healing fluid, much as blood vessels do, and the network can be refilled from a reservoir at the surface. Such materials can heal repeatedly, but the channels are difficult to manufacture and inevitably take up space that would otherwise carry load.

Intrinsic systems avoid capsules altogether. Here the polymer chains themselves are joined by bonds that can break and re-form, such as hydrogen bonds or the links produced by the Diels–Alder reaction, which opens when the material is warmed and closes again as it cools. A scratch in such a polymer can be closed simply by pressing the two surfaces together, sometimes with mild heat or ultraviolet light. Intrinsic healing is elegant and repeatable, but the reversible bonds are usually weaker than the permanent bonds they replace, so the material heals well and performs less well in the first place.

Concrete is the most widely produced material on earth, and cracking is its great weakness. Even a hairline crack admits water and chloride, which corrode the steel bars embedded in it, and repairing bridges and tunnels is expensive. One striking solution has come from a laboratory at Delft University of Technology in the Netherlands, where Henk Jonkers and his colleagues have developed concrete containing small capsules of bacteria together with calcium lactate, a compound on which the bacteria can feed. The bacteria are added as spores, which can survive for many years in dry conditions. Hardened concrete is dry and highly alkaline, so the spores remain inactive until a crack lets in water and air. They then revive and consume the food, excreting calcium carbonate, or calcite, the same mineral as limestone. The mineral gradually seals the crack.

Self-healing has begun to appear in products. Clear coatings for car bodies and for mobile phone screens contain polymers that flow into fine scratches when warmed, and self-healing hydrogels, which are networks of polymer chains swollen with water, are being developed as wound dressings and as inks for printing artificial tissue. Self-healing rubber and sealants are sold for use in cables and pipes. These are modest applications, however: they deal with surface damage, and the material behind the surface is untouched.

The obstacles to wider use are practical as much as scientific. Cost is the main one, since capsules and catalysts are expensive and are added to materials that are made in enormous quantities at low prices. Embedding capsules also weakens a material slightly, because every capsule is a void where there should be load-bearing solid. Healing is limited to damage smaller than the capsules themselves, so a structural crack a centimetre wide is beyond the reach of the technology. And proving that a material will still heal after twenty years in a bridge, rather than after a week in a laboratory, takes twenty years.

Research has therefore turned towards materials that do several things at once. Laboratories are developing composites that sense strain, report damage and repair it, and batteries and electronic circuits whose electrodes and connections can recover from cracking. A quieter line of work tries to copy the way bone remodels continuously, using bacteria or other living cells embedded in a material to deposit new mineral where it is needed. Whether any of this will leave the laboratory is another matter.

For most of the past decade, anyone with an interest in education has been asked to choose a side. Are recorded lectures and online seminars the future, or are they a thin substitute for the real thing? The argument is usually presented as a contest in which one model must defeat the other. That framing seems to me to be the source of much of the confusion. Online study and classroom teaching are not rival versions of the same experience; they are different instruments, and the useful question is what each of them does well.

Online provision has one undeniable advantage: it does not require anyone to be in a particular place at a particular time. Students who care for children or elderly relatives, who live far from a campus, who have disabilities that make travel difficult, or who work shifts can study when they are able to. Recorded material can be watched twice, paused or slowed down, which a lecture theatre cannot offer. These are not small conveniences. For a great many people they are the difference between studying and not studying at all.

The room has advantages that are harder to quantify but no less real. A teacher standing in front of thirty students can see who is lost and change the explanation on the spot; a screen shows faces, or nothing at all. Discussion in a classroom has a rhythm and a civility that video conferencing struggles to reproduce, because only one person can speak at a time and the small signals of disagreement — a frown, a raised eyebrow — are invisible. The classroom is also a social institution as much as an academic one: friendships, professional networks and a sense of belonging are formed there.

The research on whether students learn as much online is often summarised by the phrase 'no significant difference'. Reviews comparing online and face-to-face courses have generally found similar results in examinations, which surprises people who expect one mode to be plainly superior. Yet a difference in examination scores is a narrow measure of what education is for. It says nothing about whether a student has learned to argue, to work with others, or to persist when the work becomes dull.

The most conspicuous failure of the past fifteen years is instructive. When free online courses from prestigious universities were launched in the early 2010s, they were described as a revolution in access. Completion rates, however, were often below one in ten. That figure is regularly quoted as proof that online teaching does not work. It proves nothing of the kind: the courses were free, open to anyone and carried no credit, so signing up cost a student nothing, and abandoning the course cost nothing either.

The pandemic produced a second body of evidence, which is just as easily misread. Schools and universities closed, and teaching moved onto screens within days. Learning was lost, particularly by younger and poorer pupils. But what happened in 2020 was not online education; it was emergency remote teaching, improvised by people who had never been trained for it, often with poor equipment and no time to design anything. It would be as reasonable to judge classroom teaching by a substitute teacher with no lesson plan.

Age is the variable that matters most. Online study demands a degree of self-regulation — planning, monitoring and resisting distraction — that most children, and many adolescents, have not yet developed. A screen that offers a lesson also offers everything else on the internet. For a nine-year-old, the physical school provides not only instruction but supervision, meals, exercise and somewhere to be while parents work.

Assessment raises a further difficulty that has little to do with teaching and everything to do with trust. An examination taken in a room can be supervised; an examination taken at home cannot, at least not without monitoring software that many students find intrusive and many institutions find unreliable. The result has been a retreat towards timed essays and open-book papers, which measure something slightly different. Whatever the merits of these compromises, they are a reminder that a course is a system, and that changing where students are changes almost everything else as well.

There is also a commercial interest that should be named. Online provision appeals to administrators because it can be delivered to far more students without building more classrooms, and it appeals to investors for precisely the same reason. When the case for online teaching is put mainly in terms of cost per student, something has gone wrong. A model adopted because it is cheap will be cheap in every respect.

None of this is an argument for the lecture theatre as it has always been. A recorded explanation that a student can revisit is better than a live one delivered once and lost, and there is no good reason for a lecturer to read aloud material that could be read at home. The blend I would defend is one in which routine transmission of information happens online. The classroom would then be kept for argument and for practical work. It would also be kept for the kind of teaching that requires a human being in the room. That is an expensive model, and it is worth saying so. The classroom has survived every previous technology that was said to make it obsolete, from the printed textbook to television, and it will probably survive this one too.