Đề thi thử TOEFL Junior Challenge năm học 2026-2027 - Reading Comprehension

The Grade 7 field trip to the museum will be on Wednesday, November 18, so the two tests planned for that day have been moved. Each test will cover only Units 5 and 6, so you do not need to study the other units. Please read the new schedule below carefully.

Students who are sick on a test day should tell their teacher as soon as they return to school. Please remember that the new dates are final.

Dear Ms. Alvarez,

I am writing on behalf of the Westlake Robotics Club. Mr. Hale founded our club last September, and we now have fourteen members. We meet after school to share ideas and test our designs. At the moment, we are building a robot for the regional contest, and we want to do our best.

Unfortunately, Mr. Hale transferred to another school last month, leaving the club without an adviser. The principal stipulated that students may use the science lab only when an adult adviser is present. She also clarified that the school cannot choose an adviser for us, so the club must secure one independently. Because of this rule, our work has stopped for now.

We have already approached the other science teachers, but they all have prior commitments and cannot help. Last year, in your science class, you allowed every group to present its own bridge design and provided constructive feedback. We would like the same kind of support for our robot. Our meeting times are flexible, so we can adjust to your schedule.

I can bring photos of our robot so that you can see our progress. May we meet with you this week to talk about it? Thank you very much for considering our request.

Yours sincerely,

Priya Nair

Every autumn, the leaves of many trees change from green to yellow, orange, red, or brown. This change is the result of chemical processes that begin when the days grow shorter. In spring and summer, leaves are green because they contain chlorophyll, a green pigment. Pigments are substances that give color to plants and animals. Chlorophyll captures energy from sunlight, and the tree uses this energy to turn water and gases from the air into sugar. All summer, each leaf works like a small food factory.

As autumn arrives, the days become shorter and the nights become cooler. The leaves receive less sunlight and can make less food, so the tree starts to prepare for winter. It stops making new chlorophyll, and the chlorophyll that remains slowly breaks down. Before the leaves fall, the tree pulls some useful materials out of them and stores these materials in its branches and roots. As the green fades, yellow and orange pigments appear. These pigments were in the leaves all summer, but the strong green color hid them.

Red and purple leaves have a different story, because their color is not simply uncovered. It is made new. As autumn goes on, a thin layer of cells forms at the base of each leaf stem. This layer slowly blocks the stem, so the sugar made in the leaf cannot travel out to the rest of the tree. The trapped sugar accumulates in the leaf, and in bright light it changes into anthocyanin, a red pigment. The amount a leaf makes depends on sunlight. For example, a leaf on the sunny side of a maple may turn deep red, while a leaf on the shaded side of the same tree turns only yellow. Some oak leaves turn brown instead, because of waste substances that stay in the leaf.

Weather strongly affects how bright the colors will be each year. The best displays usually follow warm, sunny days and cool nights that stay above freezing. Such weather lets the leaves make plenty of sugar during the day and keep it at night, so more anthocyanin forms. Cloudy weather has the opposite effect, because the leaves make less sugar and the reds look weaker. An early freeze can be even worse, because it can damage the leaves before their colors fully develop. Eventually, the layer at the base of each stem becomes complete, and the leaf falls.

Hearing begins when something makes the air vibrate. These vibrations, which we call sound waves, travel down the ear canal and make the eardrum, a thin sheet of tissue, move back and forth. Behind the eardrum, three tiny bones pass the movement on to the inner ear. There, thousands of hair cells detect it. Hair cells are very small cells with hairlike tips. When a vibration bends these tips, the cell produces an electrical signal. Nerves carry the signals to the brain, and the brain turns them into the sounds we recognize.

The loudness of a sound is measured in decibels. A normal conversation measures about 60 decibels. The scale does not rise in equal steps, however. Every increase of ten decibels means ten times more sound energy. A rock concert, at about 110 decibels, therefore carries far more energy than a conversation, not just a little more. Loudness is only part of the danger, because time matters too. Safety experts who study noise at work suggest a daily limit of 85 decibels for eight hours. For every three decibels above that level, the safe listening time is cut in half.

Hair cells are tiny, and they are vulnerable. A single very loud noise may bend them too far, and a long period of noise may wear them out. The damage is serious because human hair cells do not grow back. Once they are gone, the hearing they provided is gone, too. Often the first warning is temporary. After a loud concert, a person may hear a ringing or buzzing that no outside source is making, or find that voices sound dull and unclear. These effects often fade after a few hours or days. Still, they show that the ears were being pushed too hard.

Damage does not always come from one dramatic event. Small amounts of harm can take their toll over many years, so a person may not notice any change at first. This is one reason hearing experts pay attention to ordinary sources of noise. Power tools, lawn mowers, and music played through headphones at a high volume can all reach levels near or above the daily limit. By the time a person notices that conversations have become hard to follow, some of the hair cells may already be lost.

The bicycle did not materialize in its final form. Instead, it went through a gradual evolution over roughly a century, and virtually every successive design was meant to compensate for a flaw in the one before it. The earliest machines, assembled in the early 1800s, were cumbersome. Made from a heavy wooden frame and mounted on two wooden wheels, they had no pedals whatsoever. Riders accordingly had to advance by pushing against the ground with their feet, a demanding approach that was exhausting even over short distances.

The solution, which emerged in the 1860s, was to fasten pedals directly to the front wheel. Riders could at last lift their feet off the ground, and the machines became significantly faster. Nonetheless, the new design brought setbacks of its own. Because the frame and wheels were still made chiefly of wood, the impact of every stone in the road was transmitted directly to the rider. People soon labelled it the "boneshaker." There was a second disadvantage as well. With the pedals fixed to the front wheel, one turn of the pedals moved the bicycle forward by precisely one turn of that wheel. The only way to attain greater speed was therefore to build a larger wheel.

Manufacturers adopted that logic in the 1870s, producing machines with an oversized front wheel. Since a larger wheel covered more ground with each turn of the pedals, riders could sustain substantially higher speeds, and the new machines rapidly gained popularity. The sacrifice made for that speed was safety, however. The seat was positioned high above the ground, almost directly over the front wheel, so if the wheel encountered a rock, the rider was frequently thrown forward over the handlebars. Falls of this kind were common and could cause fractures and other serious injuries.

The next phase finally tackled the problem of safety. In the 1880s, manufacturers resorted to two smaller wheels of equal size and positioned the seat low, between them. The decisive modification was a chain connecting the pedals to the rear wheel, which was an ingenious solution. Thanks to the chain, the rear wheel could rotate several times for every turn of the pedals, so a small wheel could match the speed of the old giant one. Soon afterwards, manufacturers began equipping bicycles with rubber tires filled with air, which absorbed much of the vibration from the road. The outcome was a machine that integrated speed, stability, and comfort, and its fundamental design became the prototype of the bicycles we ride today.