A cow, like all mammals, produces milk to feed its young. If its calf nurses regularly, the mother cow’s mammary glands will produce enough milk to give the baby animal all the food it needs. Gradually a calf will nurse less as grass and other feed makes up more of its diet. A mother cow, in turn, will produce less milk until it is no longer needed. But by milking the cows regularly—two or three times a day—dairy farmers can cause the cows to continue producing milk. Certain breeds of cows are particularly good at milk-making, producing 18–27 pints (around 2–3 gallons, or 10–15 liters) each day.
A cow’s large, round udder, located on its underside, has four nipples, or teats, that are squeezed to release stored milk. While once done by hand, milking is done on modern dairy farms by machines with suction hoses, which do the job more quickly and cheaply. Tank trucks collect milk from farms daily and take it to processing plants where it is pasteurized (made germ-free) and used to make dairy products like cheese, butter, and ice cream.
An ear thermometer reads the spectrum of thermal radiation given off by the inner surfaces of a person’s ear. All objects give off thermal radiation (including the light emitted by a glowing incandescent light bulb) and that radiation is characteristic of their temperatures. The hotter an object is, the brighter its thermal radiation and the more that radiation shifts toward shorter wavelengths.
The thermal radiation from a person’s ear is in the invisible infrared portion of the light spectrum, which is why you can’t see people glow. But the ear thermometer can see this infrared light and it uses the light to determine the ear’s temperature. The thermometer’s thermal radiation sensor is very fast, so it can measure a person’s body temperature in just 168 a few minutes.
Known as the “Giant Water Platter,” South America’s giant Amazon water lily has strong leaves that reach 6 to 8 feet (1.8 to 2.4 meters) across and can support the weight of a child. The water lilies produce flowers that open at night and are the size of a dinner plate. The first night they are white female flowers; on the second night they turn to pink male flowers.
Beetles and sphinx moths that live in the Amazon River region pollinate the flowers and the seedpods—that are the size of a baby’s head—sink beneath the water, where they lay dormant in the mud for up to four years before germinating. The plant lays dormant for a period every year before producing more leaves that increase in size before it flowers again. However, the giant water lily’s leaves are not the biggest on Earth. Palm trees can grow leaves up to 65 feet (20 meters) long!
Everyone with children has kissed a small bruise or cut to make it better. This comes from one of our earliest medical procedures for the treatment of snakebite. Noticing that a victim could be saved if the venom was sucked out through the point of entry, early doctors soon began treating all infectious abrasions by putting their lips to the wound and sucking out the poison.
Medicine moved on, but the belief that a kiss can make it all better still lingers.
In the Arctic and Antarctic circles there is at least one day a year when the Sun does not rise and one day when the Sun does not set. This is because of their close location to Earth’s poles.
The Sun does not set on the summer solstice (June 21 in the north and December 21 in the south) and does not rise on the winter solstice (December 21 for the north and June 21 for the south). For this reason, the Arctic and Antarctic are called the “lands of midnight Sun” in the summer and “lands of noon darkness” 12 in the winter.
Disease and poverty exist all over the world. The areas with the most disease and poverty are countries in sub-Saharan Africa and the Asia-Pacific region. In these areas, people do not have enough food to eat, water to drink, or money to live.
They have diseases like AIDS, which weakens the immune system, and cholera, an intestinal infection. In the United States, about 33 million people live in poverty, according to government statistics. Almost 12 million of these people are children, and about 3.5 million were age 65 or older.
The Internet is an amazing place where you can find information on all kinds of things. You can chat with friends, e-mail long-distance pen pals, and read what other people are saying about things you are interested in. But just as you should not talk to strangers when you are in the outside world, you should also use caution when chatting in the cyber world. Unfortunately, there are people surfing the Web who present a threat to kids.
They may be adults posing as another kid or somehow lying to you about who they are and what they want. To be safe, never give anyone you don’t know personal information about yourself online—including your name, address, phone number, or e-mail password. And never agree to meet a person you’ve chatted with online, even if that person seems friendly or harmless. Let your parents know if a stranger is sending you e-mail or instant messages.
Some children do better in school than others for many reasons. All kids have different talents and abilities, and some of these just show up better in school. Some children may be naturally better at reading and writing, working with numbers, and at storing and using information.
Some children are very organized, good with managing their time, and diligent about doing their homework. Most schoolwork requires these skills, so kids who are strong in these areas are likely to be better students. Still, most kids have enough ability to earn the basic skills taught in schools, things that they will need to know to get along well in the world once they graduate. Kids succeed by putting a lot of time and effort into their studies, by getting help when they need it, and by not giving up!
There are many organizations in the United States and all over the world that study and research plant and animal species, determining which ones may be headed for extinction (when a species of plant or animal dies out completely). Any species in such danger is described as “endangered.” Once a species is endangered, it becomes illegal to hunt that animal or destroy its habitat.
In 2008 the U.S. Fish and Wildlife Service, the organization that maintains the nation’s list of endangered and threatened plants and animals, listed more than 1,000 animals worldwide (“threatened” species are those that might soon become endangered). The goal of such organizations is to help a species recover to the point that it no longer needs to be listed as endangered.
The expression “frog in your throat” doesn’t come from sounding like a frog because you have a cold or sore throat. It originates from an actual Middle Ages medical treatment for a throat infection.
Doctors believed that if a live frog was placed head-first into a patient’s mouth the animal would inhale the cause of the hoarseness into its own body. Thankfully, the practice is long gone, but the expression “frog in your throat” lives on.