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.
Human beings communicate through language, a complicated system of vocal symbols that our complex brains allow us to learn after we are born. But we also communicate through our bodies and senses. Our organ of touch is our skin, covering the outside of our bodies. (Nerve endings under the surface of skin give us our sense of touch.) Hugging and kissing are ways to share love and caring through touch. When you were born, well before you knew language and could understand caring words, you were learning about love through your sense of touch. As a newborn, when everything was frighteningly new, you immediately experienced the comfort of touch when you were held in your mother’s arms, feeling the warmth of her body and the beat of her heart, sensations familiar to you when you were inside her womb. You were held close when you first learned about food and about how good it felt to have milk in your empty stomach.
Your parents’ caring hands kept you clean and dressed in dry clothes when you could not yet do those things for yourself. So, from your earliest days, you learned that someone’s touch usually made you feel comfortable and safe. Loving and caring about special people in our lives is a feeling inside that is hard to describe in words. But hugs and kisses make it easy to show that love—and their message is clear. Giving hugs and kisses feels as good as getting them. (Because the lips have an extra supply of nerve endings, kissing is an especially intense way to touch.) The human need to share affection through touch is something we all experience throughout our lives.
Jupiter, Saturn, Uranus, and Neptune have rings—or thin belts of rocks—around them. Jupiter’s ring is thin and dark, and cannot be seen from Earth. Saturn’s rings are bright, wide, and colorful. Uranus has nine dark rings around it, and Neptune’s rings are also dark, but contain a few bright arcs.
At one time all of the planets, Earth included, had rings. These rings were unstable and the material was either lost in space or collected into the satellites of these planets.
Most adult insects, including bees and dragonflies, have two large compound eyes, made up of separate, sometimes thousands, of lenses. They all point in different directions to give the insect a very wide field of vision.
The lenses also help the insect see movement, enabling it to react quickly to seize its prey or escape danger. You can witness this yourself as you try to swat a fly in your home it’s almost impossible to catch a flying insect!
Fixed groups of stars that seem to form a particular shape, such as that of a person, animal, or object, are called constellations. Astronomers have identified 88 constellations and many of them represent characters from Greek and Roman mythology.
For example, the name Hydra, the largest constellation, comes from the water snake monster killed by Hercules in ancient mythology. Some of the constellation names are in Latin; for example, Cygnus means Swan and Scorpius means Scorpion.
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!
The dandelion and the daisy are both named for a particular physical characteristic. The English daisy, with its small yellow centre and white- or rose-coloured rays, closes at night and reopens with daylight like the human eye, and so it was named the “day’s eye.”
The dandelion, because of its sharp, edible leaves, was named by the French “dent de lion,” the “tooth of a lion.”
Pen pals (also called pen friends) are people who regularly write to each other, particularly via postal mail. They are often located in faraway places, such as other states and countries. A pen pal relationship is often used to practice reading and writing in a foreign language, to improve literacy, to learn more about other countries and lifestyles, and to feel connected to people in other parts of the world which helps the world feel like a much smaller place! Pen pals come in all ages, nationalities, and cultures.
Pals may seek new pals based on their own age group or a shared common interest, such as a specific sport or hobby, or they may select someone totally different to gain knowledge about a foreign culture (such as the Far East, Europe, or South America). With the advent of the Internet, a modern version on the traditional pen pal arrangement has developed, and many pen pals also exchange e-mail addresses as well as, or instead of, paper letters. In order to connect with a pen pal, get your mom or dad’s permission first. Often, online sites dedicated to pen pal communication can help you connect with a student your own age.
The term “white elephant” comes from ancient Siam, where no one but the king could own a rare and sacred albino, or white, elephant without royal consent.
The cost of keeping any elephant, white or otherwise, was tremendous, and so when the king found displeasure with someone he would make him a gift of a white elephant, and because the animal was sacred and couldn’t be put to work, the cost of its upkeep would ruin its new owner.
The first primitive plants appeared on land about 470 million years ago. But these plants did not look like the lush greenery we see in the world today. Rather, they were rootless patches of thin, leaflike plants called liverwarts, so named because some species look like green livers. Liverwarts used a specialized filament (called a rhizoid) to absorb water and stick to rocks.
Fossils reveal that the first true plants to colonize land appeared about 420 million years ago. These plants included flowerless mosses, horsetails, and ferns. They reproduced by throwing out spores, or minute organisms that carried the genetic blueprint for the plant. The ferns eventually bore seeds, but not until about 345 million years ago. Plants with roots, stems, and leaves (called vascular plants) evolved about 408 million years ago.