IELTS Academic Reading Practice Test 418

When the organisers of the World's Columbian Exposition began planning the fair that would open in Chicago in 1893, they faced an obvious comparison. The Paris Exposition of 1889 had left behind the Eiffel Tower, a structure that had drawn millions of visitors and had come to stand for French engineering. The Chicago fair was intended to celebrate the four hundredth anniversary of Columbus's arrival in the Americas, and its directors wanted a centrepiece that would rival the tower in scale and boldness. A committee invited engineers to propose something that had never been seen before.

Among those who responded was George Washington Gale Ferris Jr., a civil engineer from Pittsburgh. Ferris had studied at the Rensselaer Polytechnic Institute and had later founded a company that tested and inspected steel for railways and bridges. His work had given him a practical knowledge of heavy metalwork, but he had never designed a structure intended for public entertainment. His idea was a gigantic revolving wheel, carrying passengers in cars suspended from its rim. The committee rejected the scheme at first, judging it unsafe and too expensive; only after further lobbying and a revised estimate was it approved in the closing weeks of 1892.

The design was simple in outline and difficult in execution. Two tall steel towers would support a central axle, and from the axle a pair of enormous rims would be braced by spokes. The wheel would stand about eighty metres high, roughly the height of a twenty-five-storey building, and would be about seventy-five metres across. Thirty-six cars, each the size of a tram, were hung around the circumference. Each car could hold up to sixty people, with seats for some and standing room for the rest, so that a full turn of the wheel would carry more than two thousand passengers.

The axle was the critical component. It had to bear the weight of the wheel and its passengers while turning freely, and no single piece of steel of that size had been made before. The axle used in Chicago weighed more than forty tons and was forged in one piece, then carried to the site by rail. The two towers that held it were themselves tall enough to dwarf the surrounding buildings. Power came from two steam engines, linked to the wheel by a system of gears. Engineers calculated that the structure would withstand the wind and the load, but the fair's directors remained nervous until the first trial.

Construction began in the winter of 1892–93 on the Midway Plaisance, the strip of land that led to the main fairground in Jackson Park beside Lake Michigan. The ground was frozen, and the excavation for the foundations was slow and difficult work. Work went on through bad weather, and the wheel was still unfinished when the rest of the fair opened on 1 May 1893.

Visitors could see the towers rising above the white buildings of the fairground, but the wheel did not begin carrying passengers until 21 June, seven weeks after the official opening. The delay added to the anxiety of the organisers, who had promised a wonder; it also increased the crowd's curiosity.

Once it started, the wheel worked smoothly. Passengers entered the cars at the bottom, and the wheel stopped while each car was loaded. A ride cost fifty cents, a considerable sum for many visitors, and lasted about twenty minutes. The wheel made two complete turns: the first slow, with stops for boarding, and the second without stopping, so that riders could look out over the fair and the lake beyond. From the top they saw the exhibition buildings, the crowds and the flat shore of Lake Michigan. The movement was gentle enough for most passengers, though some found the height alarming.

The wheel quickly became the fair's most photographed attraction. More than a million passengers are said to have ridden it during the five months of the exhibition, and the queues were often long. It made money for its promoters, although not as much as they had hoped, because the cost of building and running it had been enormous. Its success encouraged other inventors and showmen, who saw that a large wheel could draw a paying crowd. For the visitors, however, the appeal was simpler: it offered a view that no building in Chicago could provide.

Not everyone approved. Some clergymen and moralists complained that the wheel encouraged idle pleasure, and a few engineers doubted that it was safe. The fair's own authorities inspected it repeatedly. At night it was lit by electric lamps, so that it remained visible across the fairground after dark. In the end, no serious accident occurred, and the wheel's record helped to answer the critics. Its design was copied in other cities, and the name of its inventor became attached to the machine itself.

After the fair closed in October 1893, the wheel was taken down and placed in storage. Some time later it was rebuilt on the North Side of Chicago, near Lincoln Park, and operated there until 1903. It was then sold and moved to St Louis for another great fair, the Louisiana Purchase Exposition of 1904. In 1906 it was broken up and the metal sold as scrap. Ferris himself did not live to see this end: he died in 1896, at the age of thirty-seven, after a short illness. The wheel had lasted barely a decade, but its influence lasted much longer, and large wheels remain a familiar feature of fairs and city skylines.

Bread can be raised in two quite different ways. The first relies on a measured dose of a single commercial yeast; the second depends on a community of wild yeasts and bacteria that a baker keeps alive in a mixture of flour and water. This mixture, known as a starter, a leaven or a mother, has been used for thousands of years, and it is only in the last century and a half that the alternative has become common. A sourdough loaf, in other words, is the product of an ecosystem rather than a single ingredient.

The organisms involved fall into two groups that do different jobs. Yeasts, which are single-celled fungi, ferment sugars and release carbon dioxide and ethanol; it is the carbon dioxide that makes dough rise. Lactic acid bacteria, which are far more numerous in most starters, produce acids instead. Neither group can digest starch directly. Both depend on enzymes in the flour, chiefly amylases, which break damaged starch down into sugars. The most abundant of these sugars is maltose, which yeasts and bacteria ferment readily. The two populations therefore compete for the same food, and the balance between them determines how quickly a dough rises and how sour it tastes.

A starter is maintained by a simple routine. The baker keeps back a portion of the fermented mixture and adds fresh flour and water, usually discarding some of the old culture first. This process, called back-slopping, supplies new food and dilutes the acids that have accumulated. Regular refreshment keeps the acidity within limits that suit the desired microbes while making life difficult for others; a starter that is left unfed for too long becomes exhausted, and unwanted organisms may take over. Many bakers judge the health of a starter by how quickly it doubles in size after feeding.

Although a starter may contain dozens of kinds of microbe, the number that matter is usually small. Certain species appear again and again in starters from very different places. Among the bacteria, a species long known as Lactobacillus sanfranciscensis, first identified in the early 1970s in starters used by bakeries in San Francisco, is particularly common; among the yeasts, one called Kazachstania humilis often dominates. The mixture also shifts with temperature and with the type of flour used, so that a starter kept in a cool kitchen and one kept in a warm bakery may behave quite differently even if they began from the same dough.

During fermentation the dough becomes a trap for gas. Kneading develops gluten, the network of proteins that gives dough its elasticity, and the bubbles of carbon dioxide released by yeast are held within it. Acids change the behaviour of this network: as the dough becomes more acidic, the gluten becomes less elastic and more extensible, so that it stretches further before tearing. This is one reason why a long, slow fermentation can produce a loaf with a more open texture than a quick one, although the effect also depends on the strength of the flour and on how the dough is handled.

The acids themselves are of two main kinds, and their proportions shape the flavour. Lactic acid is mild and slightly yoghurt-like; acetic acid is sharper, and in sufficient quantity gives the vinegary note that some loaves carry. Bakers generally find that a stiff dough, a cooler fermentation and a longer time favour acetic acid, whereas a wetter, warmer dough favours lactic acid. Acidity has other effects: it slows the growth of mould, and it changes the starch so that the crumb firms up more slowly after baking.

Other changes happen at the same time. Wholemeal flour contains phytate, a compound that binds iron, zinc and magnesium and prevents the body from absorbing them; the enzymes produced by sourdough microbes break much of it down, so that the minerals become more available. Long fermentation also reduces the amount of fructans, carbohydrates that some people find hard to digest, which may explain why sourdough bread suits some of those who avoid ordinary loaves. It does not, however, make bread safe for people with coeliac disease, and claims to the contrary should be treated with caution.

What remains uncertain is where the microbes come from. Bakers have long assumed that a starter captures the yeasts and bacteria floating in the air of a particular bakery, and that this is why local bread tastes distinctive. Studies comparing starters from different countries have cast doubt on this: organisms seem to arrive mainly with the flour, and starters maintained far apart often end up with similar communities. Whether differences in flavour come from the microbes themselves or from the way the dough is handled is still disputed.

A starter, well looked after, can be kept going for decades. Some bakeries maintain the same culture year after year, and a few families have passed one down for generations. In practice, though, the microbes matter less than the baker's management of time, temperature and moisture. A starter is not a secret ingredient so much as a tool that rewards attention.

Who should be offered a place at a selective university, and on what evidence, is one of the most contested questions in education. The argument has become sharper as participation has widened: when only a small proportion of school-leavers applied, selection could be informal, but as governments have encouraged far more young people to aim at degree courses, competition for places at the most sought-after institutions has intensified. Entrance examinations of some kind — the SAT and ACT in the United States, a single national or regional examination in parts of East Asia, school-leaving grades in England — now sit at the centre of the argument. Should they be scrapped?

The case for keeping them is easily stated. A school's own assessment may be generous or severe, and grades awarded by different schools are not directly comparable; a national test at least applies the same ruler to everyone. Because scripts are marked without the candidate's name, tests also offer some protection against favouritism, against the letter of recommendation from a family friend and against the interview that goes well because of confidence rather than ability. Defenders add that test scores predict performance in the first year of a degree reasonably well, and that they are cheap to administer compared with interviews, portfolios and auditions. They warn, too, that grades can be inflated, so that a school which marks generously gives its pupils an advantage unrelated to their ability.

Critics reply that the ruler is not neutral. Scores rise with family income, with the commercial coaching a family can afford and with the education of a candidate's parents; a test that measures these things cannot honestly be described as a measure of merit. In their view, the examination does not so much assess ability as record the advantages a candidate has already enjoyed. They argue, too, that the skills examined — rapid comprehension and calculation under time pressure — say little about qualities that matter at university, such as persistence or the ability to sustain a long project. And because schools are judged on their results, a high-stakes test tends to narrow what is taught.

The research evidence is less decisive than either side suggests. Studies in several countries have found that school grades predict success at degree level at least as well as standardised tests, which is a serious point for those who would keep the tests. Yet grades are not equally informative everywhere, and some analyses suggest that test scores add useful information about applicants from schools that send few students to university. When many American universities made the tests optional during the pandemic, early reports suggested that the change had altered the composition of the incoming class less than campaigners had hoped.

Countries that rely on a single examination offer a warning. Where one score decides everything, families invest heavily in private tutoring, and the competition becomes a contest between those who can pay for it and those who cannot. The pressure on candidates is intense, and the temptation to cheat — leaking papers, impersonating a candidate — grows with the stakes. Some systems set different papers in different regions and check the identity of candidates at the door. Yet abolishing the examination in such systems, where school assessment is uneven and sometimes corrupt, would probably shift advantage towards families with connections rather than reduce it.

My view is that the argument has been wrongly framed. The difficulty is not the existence of the test but the use made of it. A score is a piece of evidence with a margin of error, and treating it as a threshold turns a rough signal into a verdict. An applicant who misses a cutoff by a few points is not thereby less able than one who clears it. Once universities use scores as one item in a wider judgement, together with school records and an account of the opportunities available to the candidate, most of the objections lose their force.

Other methods of choosing among applicants have their own costs. A lottery among all who meet a minimum standard would be transparent and cheap, and it would certainly break the association between money and admission; but many people find it hard to accept that a place should be decided by chance, and it removes any incentive for applicants to demonstrate what they can do. Interviews and portfolios allow judgement of qualities that tests miss, but they are time-consuming, inconsistent between assessors and vulnerable to the advantages of the confident and the well-coached. Coaching also improves scores on tests that are supposed to measure aptitude rather than learning, which weakens the distinction.

So the sensible reform is neither abolition nor reverence. Universities should keep entrance examinations, reduce the weight they carry, publish the data that show how their use affects who is admitted, and read the results alongside school records and the circumstances in which they were achieved. That policy will not satisfy those who want a single clean measure, nor those who want none at all. But it recognises what the evidence shows: that tests carry real information and real bias at the same time. Nor can the question be settled by evidence alone, since it involves a judgement about what a university is for.