The blue whale, who swims all of the world’s oceans, in the largest mammal. The largest blue whale cited was at least 110 feet (33.5 meters) long and weighed 209 tons (189,604 kilograms). The average length is about 82 feet (25 meters) for the males, and 85 feet (26 meters) for the females. A newborn blue whale can weigh anywhere from 2.5 to 4 tons (2,268 to 3,628 kilograms), and can reach 100 to 120 tons in adulthood. Whale calves drink 50 to 150 gallons of its mother’s milk per day, adding about 8 pounds (3.6 kilograms) of weight per hour, or 200 pounds (90.7 kilograms) per day.
At about eight months of age, when the calf is weaned, it measures close to 50 feet (15.2 meters) long and weighs about 25 tons (22,679 kilograms). Blue whales do not have teeth. Instead, in their upper jaw they have rows of hundreds of baleen plates—flat, flexible plates with frayed edges, arranged in two parallel rows that look like combs of thick hair. The blue whale feeds on a small shrimp-like animal called krill. Scientists believe that large marine mammals, like whales and dolphins, have brains much like those of humans. They are able to communicate, follow instructions, and adapt to new environments. Throughout history, these gentle giants have been hunted for their baleen and blubber (fat), and are today considered an endangered species. Scientists believe there are about 4,000 or so of them left in the world.
Because one meaning of the word “bald” that is not commonly used anymore refers to white markings. “Bald” used to refer to people with white hair. Due to excessive hunting, environmental pollution, and loss of habitat, the bald eagle population became dangerously low at one point, prompting the U.S. Congress to pass a law protecting it. Bald eagles were once listed by the U.S. Fish and Wildlife Service as an endangered species, meaning they were close to being extinct. Thanks to the laws protecting it, these birds have rebounded a bit. They are now listed as threatened, which means they are not as close to being extinct as they once were, but their numbers are still few (only about 50,000 in the United States), and it is illegal to hunt them.
The practice of using laurels to symbolize victory came from the ancient Greeks. After winning on the battlefield, great warriors were crowned with a wreath of laurels, or bay leaves, to signify their supreme status during a victory parade.
Because the first Olympics consisted largely of war games, the champions were honoured in the same manner: with a laurel, a crown of leaves. To “rest on your laurels” means to quit while you’re ahead.
Although D-Day has become synonymous with the Allied landing on June 6, 1944, in Normandy, it was used many times before and since. The D in D-Day simply stands for “day,” just as the H in H-Hour stands for “hour.” Both are commonly used codes for the fixed time when a military operation is scheduled to begin. “D minus thirty” means thirty days before a target date while “D plus fifteen” means fifteen days after.
The surface of a liquid is the seat of a special force as a result of which molecules on the surface are bound together to form something like a stretched membrane. They tend to compress the molecules below to the smallest possible volume, which causes the drop to take a round shape as for a given mass he sphere has minimum volume.
Approximately 2,500 years ago the Pythagoreans defined a “perfect” number as one for whom the sum of its divisors, excluding itself, equals the number itself. For example, 6 can be divided by 1, 2, 3, and 6. If you add these numbers together, excluding 6 itself, the total is 6. Therefore 6 is a perfect number. Over the centuries, many mathematicians from all over the world have contributed to finding and defining perfect numbers.
Each calendar year is exactly 365 days, 5 hours, 48 minutes, and 46 seconds. This is the amount of time between two successive crossings of the celestial equator by the Sun at the vernal equinox (the first day of spring). The fact that the year is not a whole number of days has affected the development of calendars, which over time generate an error.
The current calendar we use, called the Gregorian calendar, attempts to fix this by adding an extra day to the month of February every four years. These years are called “leap years.”
The greenhouse effect describes a warming phenomenon. (In a greenhouse, closed glass windows cause heat to become trapped inside.) The greenhouse effect occurs when a planet’s atmosphere allows heat from the Sun to enter, but refuses to let it leave. A good example of the greenhouse effect can be found on Venus.
There, solar radiation penetrates the atmosphere, reaches the surface, and is reflected back into the atmosphere. The re-radiated heat is trapped by carbon dioxide, which is abundant in Venus’s atmosphere. The result is that Venus has a scorching surface temperature of 900 degrees Fahrenheit (482 degrees Celsius). The greenhouse effect can also be found on Earth and in the upper atmospheres of the giant planets: Jupiter, Saturn, Uranus, and Neptune.
As a boy, Benjamin Franklin was sharpening tools in his father’s yard when a stranger carrying an axe came by and praised the boy on how good he was with the grindstone. He then asked Franklin if he would show him how it would work on his own axe. Once his axe was sharpened, the stranger simply laughed and walked away, giving young Franklin a valuable lesson about people with “an axe to grind.”
Libraries offer books for people of all ages, and much, much more—they are places of learning and discovery for everyone. Besides books, public libraries offer videos, DVDs, free access to computers and the Internet, and many literacy-related programs.
For elementary school children, there are variations of the read-alouds and storytelling hours that often include discussions and presentations by the children themselves, as well as summer reading programs. For middle-school kids, there may also be book talks, summer reading programs, creative writing seminars, drama groups, and poetry readings. The more you read, the more you learn! In addition, the library is a place to find information and help with schoolwork. Your school library may offer some of these services as well.