The bicycle, often called the most efficient form of transportation ever invented, has a rich history. The earliest version appeared in the early 19th century and was made of wood, with no pedals. Riders had to push themselves along with their feet. In the 1860s, pedals were added to the front wheel, and by the 1880s, bicycles began to resemble the modern form — with chains, equal-sized wheels, and improved comfort.

Bicycles soon became popular for both recreation and commuting. They provided a new kind of freedom — especially to women — and sparked social changes by offering independence and mobility. Even today, bicycles are used around the world for travel, exercise, and environmental sustainability.

Source: Adapted from A Short History of the Bicycle, National Geographic, 1997

THE INVENTION OF THE TOOTHBRUSH

Every day, millions of people around the world begin and end their day with a toothbrush. This simple tool, now available in a wide variety of shapes and sizes, has a history that goes back thousands of years.

The earliest form of the toothbrush was a “chew stick” used by ancient civilizations such as the Babylonians and Egyptians. These were small, thin twigs with frayed ends used to rub against the teeth. In China, around 1498, the first bristle toothbrush was developed. It used pig hair attached to bamboo or bone handles.

The modern toothbrush as we know it began to evolve in the 1930s when nylon was invented. A company called DuPont introduced the first nylon-bristled toothbrush. The synthetic material was more durable and hygienic than animal hair. Over time, toothbrushes became more efficient, with ergonomic handles, angled necks, and even electric power.

Today, the toothbrush is a standard item in every household, and dental care professionals continue to stress its importance in maintaining good health.

Source ReadTheory Activity Sheet

Many students struggle to use their study time effectively. One way to improve is to create a schedule. Set aside specific times each day for studying and stick to that routine. Avoid multitasking—focus on one subject at a time. This improves memory retention. Also, break large tasks into smaller ones. For example, instead of saying "I’ll study math today," set a goal like "I’ll complete 10 algebra problems before lunch." Finally, take regular breaks. A short 5–10-minute break after every 30–45 minutes of study can refresh your mind and improve concentration when you return.

Source: adapted from Study Skills for Success, 2004

Frida Kahlo is widely known for her deeply personal and symbolic paintings that often portrayed her emotional and physical struggles. Her passion for painting was influenced by her life experiences, including a severe bus accident that left her with lifelong pain and disability. Despite these challenges, Kahlo's artwork continued to flourish, and she became a prominent figure in the Mexican art world. Kahlo was also involved in politics, often expressing her political views through her art. Though she gained fame later in life, her legacy continues to influence contemporary artists and movements.

Source: Frida Kahlo: A Biography, Hayden Herrera, 1983

The Mystery of Dreams 

Dreams mainly occur during a period known as REM sleep. REM stands for Rapid Eye Movement. During REM sleep, your eyes move back and forth very quickly beneath your closed lids. While you are in REM sleep, your brain is very active—almost as active as if you were awake. You are more likely to remember your dreams if you are awakened during REM sleep than if you were awakened at some other time during the night. 

The fact that we dream most often during REM sleep is one of very few facts about dreams that every scientist agrees on. Scientists do not know exactly which portion of the brain creates dreams or why we have them in the first place. 

One theory about the purpose of dreams is that dreaming helps the brain to organize and store memories. As your body relaxes, your brain processes all of the information it received during the day. While you sleep, your brain organizes the information into memories; your mind perceives this process as dreaming. Because your mind works differently when you are asleep than it does when you are awake, your dreams may seem confusing, illogical, or just downright silly. 

Another theory is that dreams allow your mind to work out difficult problems or puzzles that you encounter while you are awake. The unrealistic, free-flowing nature of dreams allows your mind to consider the problems in creative ways that you would likely never think of during your waking hours. 

Still other scientists believe that dreams are random events with no real function. According to this theory, there is no actual reason for dreaming—it is simply what happens when you go to sleep. 

As you can see, there is no scientific consensus about how or why we dream. There are many different theories, but no proven answers. Until then, you might as well just enjoy the fantastic nighttime adventures you get to go on without ever leaving your bed.

Source: ReadTheory Activity Sheet