IELTS Academic Reading Practice Test 443

Every June, in the highlands south of Cusco in Peru, the communities of Huinchiri, Quehue, Choccayhua and Chaupibanda cooperate to replace a suspension bridge. The structure crosses the Apurímac, a river flowing along the floor of a deep gorge, and it is constructed almost entirely from grass. Known as Q'eswachaka, it measures roughly thirty metres in length and slightly more than a metre in width, hanging some fifteen metres above the water. It belongs to a category of bridge that the Inca empire once maintained throughout the Andes, and it is among the very few examples still rebuilt by hand annually.

The Inca road network, known as the Qhapaq Ñan, extended for tens of thousands of kilometres along the Andes, from present-day Colombia to Chile and Argentina, and it had to cross innumerable rivers and ravines. Where a gorge was too broad for a causeway, engineers constructed bridges of woven rope, employing fibre from the tough grasses that flourish at high altitude. Spanish officials arriving during the sixteenth century described these crossings with astonishment, and some recorded that local people maintained the bridges as a form of labour owed to the state. As routes were redirected and steel and concrete replaced natural materials, almost every rope bridge disappeared.

Q'eswachaka survives because the communities regard its reconstruction as an obligation rather than a chore. The raw material is q'oya, a coarse grass growing in the wet ground beside mountain streams. Families harvest it in bunches some days before the work commences, leave it to dry slightly, then beat the fibres with stones until they soften and split. The prepared grass is rolled and twisted by hand into a cord, and successive cords are joined end to end. Manufacturing a complete bridge requires an extraordinary length of material, measured not in metres but in kilometres; the figures most frequently quoted run to several thousand metres of cord. Much of this labour is performed in the open air, in cold and frequently wet weather. The schedule is determined by long-established custom rather than by the calendar of school, office or market.

Labour is organised according to sex and age. Women and girls, working in groups, twist the fine cords, while men braid these cords into the heavy ropes that will support the weight. The walking surface, or deck, is formed from several of these thick ropes placed parallel and bound together. Two additional cables, one on either side, serve as handrails and are positioned at a height that allows a walker to grasp them. The bridge is not rigid: it sags in the centre and sways as it is crossed, and its extremities are secured to stone anchors embedded in the rock on either embankment.

Labour commences early, and the first task is demolition: the previous bridge is cut loose at both ends and allowed to fall. It plunges to the rocks below, and its remains are carried away by the current. A thin line is then conveyed across the gorge, and by means of it successively heavier ropes are hauled from one side to the other. Men on both embankments pull until the replacement cables occupy the position of the old ones.

During the second and third days four or five thick cables are stretched across and fastened, and the smaller ropes that form the deck are interwoven between them. Short cords fasten every component together, and the tension is adjusted repeatedly, since a bridge that is too tight may snap in the wind and one that is too slack will sag dangerously. The entire operation is supervised by an experienced master builder, who decides when each rope has been pulled enough.

The reconstruction is also a festival. Offerings are made to the mountains, and there is music, dancing and a communal meal. When the bridge is finished, the builders and their families walk across it in procession. The ritual is not decoration attached to an engineering project. For the communities it is the fundamental reason the project is undertaken at all, and the bridge represents a living connection between people and landscape.

In 2013 the knowledge, skills and rituals associated with Q'eswachaka were inscribed on UNESCO's Representative List of Intangible Cultural Heritage. The listing has brought visitors and a measure of official support, but it has also raised questions. Some younger villagers depart for employment in the city and do not return in June, and a tradition that depends upon dozens of willing hands is vulnerable.

A rope bridge of this description forms a catenary, the curve that a flexible cable adopts when it hangs under its own weight. The handrails are more than a safety feature, since they stiffen the whole structure and prevent the deck from twisting. The knowledge required to construct such a bridge is not recorded in writing anywhere. It is transmitted by participation, as children watch and then assist, and it resides in the hands as much as in words.

Because the bridge is replaced every year, nothing of the original material survives; what persists is the technique. That may explain why the crossing has attracted the attention of archaeologists and historians as well as tourists. It provides a rare, visible illustration of a technology maintained not by being preserved but by being repeated. It is also the achievement of a community that has decided, year after year, that the crossing is worth rebuilding.

A newborn baby opens its eyes on a world that is, at first, oddly uninformative. The image is blurred, and the colours in it appear washed out and hard to name. Parents often assume that the baby is simply too young to interpret what it sees, and that the eye itself is working perfectly. In fact the eye is a construction site. The retina, the light-sensitive layer at the back, and the nerves that carry signals to the brain are still being assembled, and colour vision in particular is a skill that has to be built. The muscles that control focusing are weak as well, so even a nearby face may be slightly out of focus. By the end of the first month the blur has begun to resolve.

Human colour vision relies on three kinds of cone, the light receptors of the retina, which respond best to short, medium and long wavelengths of light, which we may loosely call blue, green and red. Comparing the responses of the three allows the brain to distinguish millions of shades. At birth, however, the cones are not yet arranged as they will be. The fovea, a small central pit in the retina where cones are most densely packed and vision is sharpest, is immature. Its cones are short and squat, there are fewer of them, and the connections they make with the cells beneath them are still being refined. This is one reason a newborn's acuity is roughly 20/400, the level at which an adult would be judged severely short-sighted.

How can anyone know what a baby sees? Infants cannot answer questions, so researchers have learned to use behaviour instead. The American psychologist Robert Fantz established the basic method in the 1950s: if a baby is shown two patterns side by side, it will look longer at the one it can tell apart. A later refinement, habituation, presents the same stimulus repeatedly until interest fades and then introduces a new one. If the baby's looking time jumps, it has noticed the difference. In colour experiments the two stimuli differ only in hue, and a clear preference for one is taken as evidence of discrimination.

Studies of this kind suggest a timetable. Newborns can already make some colour discriminations, but they are slow and inconsistent, and their performance improves sharply at about two months. The colours are not treated equally. Differences that depend on the long- and medium-wavelength cones, roughly the discrimination of red from green, appear first. Differences that depend on the short-wavelength cones, roughly blue from yellow and green, emerge later, because those cones mature more slowly and because the lens of the eye filters out some short-wavelength light. By four to six months a baby's performance on many colour tasks is close to that of an adult.

Experience plays a part, though exactly how much is contested. The visual cortex, the region at the back of the brain where signals are interpreted, develops with use. Children born with dense cataracts, which cloud the lens and block a clear image, are usually operated on within the first months of life. Those treated early typically catch up remarkably well. Those whose sight is restored only after several years often show lasting difficulties with fine detail and with certain aspects of colour. That suggests there is a period early in life during which the system must receive clear input. The same evidence, though, shows how robust development is when the input arrives on time.

What remains genuinely uncertain? First, whether babies group colours into categories before they have words for them, or whether the categories are created by language later on. Second, the blue-yellow pathway: the exact timing of its maturation is still debated, because tests that rely on looking behaviour give slightly different answers from tests that record electrical activity in the brain. Third, how much babies differ from one another. Research on infants is also slow and laborious, since a baby's attention cannot be relied on for more than a few minutes at a time. A test that works with one child may fail with the next.

There are practical consequences. Because infants cannot name colours, it is not possible to use the standard screening tests that identify colour-vision deficiency in adults. In those tests a person is asked to pick out numbers or shapes from a pattern. Such screening must wait until a child can name colours reliably, which is usually at about three or four years of age. Meanwhile, the evidence about what babies can see is a reminder that a nursery full of bright objects is not merely decorative. Strong contrasts and sharp edges give the developing system something it can actually resolve. For parents, this may be the most useful conclusion in the field.

The subject also illuminates evolution. Most mammals possess only two kinds of cone, and the world of a dog or a horse is probably less varied in hue than ours. In species that hunt at night, colour may matter less than the ability to detect movement in dim light. The third cone in old-world primates, including humans, is thought to have arisen through a duplication of the gene for one of the others, and it may have helped our ancestors find ripe fruit among leaves. Colour vision is thus not a single ability that switches on, but a set of capacities with different histories, which in humans are assembled slowly, after birth, in the first months of life.

Few questions in education policy divide opinion as sharply as this one. In England, Sweden, Chile and parts of the United States, parents may apply to schools other than the one nearest their home, and public money follows the child. Supporters describe such arrangements as an extension of a basic freedom; critics describe them as a machine for sorting children by background. The disagreement is not really about whether parents should have choices, since wealthy families have always had them. It is about what happens when choice is extended to everyone.

The intellectual foundation of the modern debate was laid in 1955, when the economist Milton Friedman proposed that governments should fund education through vouchers that parents could spend at a school of their choosing. Competition, he argued, would oblige schools to improve or lose pupils, and parents would prove better judges of a school than distant administrators. Versions of the argument have since been adopted in many countries. Yet Friedman's model treats schooling as a straightforward consumer good, and the analogy with shops and customers is where the disagreement begins.

Sweden introduced one of the most thoroughgoing systems in 1992. Independent schools there are funded by the state at a level similar to municipal schools and paid according to the number of pupils enrolled. Swedish researchers who have examined the effects report modest improvements in attainment, particularly for pupils in the later years of compulsory schooling. On segregation the picture is less reassuring: several studies suggest that the intake of schools became more divided by parental education and immigrant background after the reform.

Chile went further and earlier. A nationwide voucher scheme was introduced in 1981, and for three decades subsidised private schools were allowed to select pupils and to charge parents additional fees. Researchers who studied the system found that it produced noticeable sorting: the most disadvantaged children concentrated in municipal schools, while better-off families moved to subsidised private ones. Gains in attainment were disputed. In the 2010s the country changed course, legislating to phase out fees and selective admissions at subsidised schools, a striking admission that a market without rules had produced unwanted results.

England offers a longer and less dramatic case. Parents there have been able to state a preference for a secondary school since the late 1980s. Yet the proportion admitted to a school other than the nearest one has stayed fairly modest, because popular schools are oversubscribed. Where choice is rationed in this way, the decisive question becomes who applies and who is offered a place, and the answer tends to follow the map of housing and income.

The evidence from the United States is patchier. Charter schools, publicly funded but independently run, have multiplied since the first state law permitting them was passed in Minnesota in 1991. Reviews of their results find wide variation: in some large cities charter pupils make substantial gains, while elsewhere they do not. Because admission is often decided by lottery when a school is oversubscribed, researchers can compare pupils who were offered a place with those who were not, which gives unusually clean comparisons.

The mechanism behind such outcomes is not mysterious. Schools that are permitted to choose will tend to choose pupils who are easiest and cheapest to teach. Parents who are confident, well informed and mobile will tend to find the schools that select them. A family new to a country, without a car or a knowledge of the admissions system, may in theory have the same freedom as a professional couple with time to visit open days. In practice it has far less. Choice is therefore not neutral: it rewards precisely those resources that schooling is supposed to distribute equally.

There is a second problem, less often noticed. The case for markets assumes that parents choose on the basis of quality, so that poorly performing schools lose pupils and either improve or close. Surveys of parents, however, consistently find that proximity, the presence of siblings at the school and a general impression of the other families who attend count for more than published results. Parents are also strongly influenced by those around them, which means that a school's reputation can rise or fall for reasons unconnected with its teaching. Competition then rewards marketing rather than improvement.

Some systems illustrate a different difficulty. The Netherlands has funded schools of different religious and educational character on equal terms since the early twentieth century, an arrangement that protects minority communities and is valued for that reason. Yet it has also been associated with high levels of separation between schools along ethnic and social lines. Freedom for groups to educate their children in their own tradition and freedom for individuals to move between schools can pull in opposite directions.

Where does that leave the question? I would argue that choice should be retained but managed. Common admissions arrangements, in which a central body assigns places rather than leaving schools free to select, remove the worst incentives to sort. Funding that follows individual pupils and gives extra weight to those from poorer families allows a school to admit them without penalty. Free or subsidised transport, and clear information about how to apply, extend the choices that matter to families who currently have none. Choice is a means, not an end; the end is a system in which a child's education does not depend on the determination of the parents.