Astronauts train a long time for their spacewalks.
Much of the astronaut training is conducted underwater.
Astronauts may spend 8 to 10 hours in the pool for every hour they will spend floating in space.
Astronauts practice to be able to perform construction and repair work on the outside of the space station.
The astronaut commanders of shuttle flights are always pilots, and many have backgrounds as military test pilots.
Other astronauts are trained as doctors, engineers, and scientists, who can run experiments in space.
Early crews were all young men, but astronauts now are much more diverse.
The team of astronauts floated out together to the exterior of the space shuttle.
The astronauts carried tools needed to repair the broken part on the huge telescope.
One astronaut loosened the bolts on the pipe, while the other fitted the replacement part into place.
Beekeeping encourages the conservation of local habitats.
It is in every interest of every beekeeper to conserve local plants that produce pollen.
As a passive form of agriculture, beekeeping does not require that native vegetation be cleared to make way for crops.
Beekeepers also discourage the use of pesticides on crops, because they could kill the honeybees.
Artisanal beekeepers go to extremes for their craft, but their product is worth the effort.
Artisanal honey-making emphasizes quality and character over quantity and consistency.
To produce the finest honey, beekeepers become micromanagers of their honeybees.
Beekeepers scout the fields, know when nectar flows, and select the best ways to extract honey.
As the beekeeper opens the hive, the deep hum of 40,000 bees fills the air.
The beekeeper checks honey stores, pollen supplies, and the bee nursery.
Bees crawl across his bare arms and hands, but they don't sting, because they're gentle.
The concert pianist went blind in adulthood.
The concert pianist's blindness was caused by a genetic condition that slowly damaged the eyes.
The concert pianist told interviewers that being blind was an advantage to a pianist.
Being blind the concert pianist had no visual distractions, so she could concentrate more fully on her music.
The government defines blindness as vision insufficient for the ordinary activities of life.
By establishing the parameters of legal blindness, resources can be focused on the legally blind.
This may overlook those who have vision problems but who do not meet the standard for blindness.
In developing countries, blindness in children is usually caused by infectious disease and nutritional deficiencies.
These causes of blindness can often be prevented by medicine and vitamin supplements.
In developed countries, blindness is more likely to be caused by genetic problems.
Hip fractures are a real problem for aging individuals.
Patients are faced with the pain of the break and the difficult process of healing the fracture.
Families have to adjust to the loss of independence of the patient with the fracture.
And for society, hip fractures involve substantial expense and time in the hospital.
Halfway through the race, I heard a sound like someone snapping their fingers.
I felt a crunch and I knew instantly that my foot was broken.
Because of the fracture, every step felt like running on spikes
At the office of the doctor afterward, the x-ray clearly showed the fracture.
There are a few different types of bone fractures.
In closed or simple fractures, the bone is broken but the skin is intact.
In open or compound fractures, the broken bone has punctured the skin and produced an open wound.
The medieval castle was not a structure built primarily for defense.
The purpose of the castle was to dominate its surroundings.
A castle could easily control lands within a day's walk.
During times of attack, peasants, livestock, and property could be brought inside the walls of the castle for protection.
Spectacular castles in dramatic locations provide a record of the stormy history of many regions.
Today, castles stand atop rocky cliffs overlooking beautiful landscapes and quaint villages.
In the past, castles were home to battles, plots and intrigue.
Upon leaving the train station we saw our hotel looming above: a magnificent castle built on a cliff.
The thick outside walls of the castle sheltered an inner courtyard hundreds of feet above the river.
Our castle tower rooms had an incredible but slightly scary view.
Computers have been used in art for a long time by experimental artists.
Now that computers are more affordable and widespread, computer graphics have entered the mainstream art world.
Some computer science conferences have art exhibitions that showcase the latest computer graphics technology.
Brand new computer graphics conferences have sprung up that are devoted to bridging the two cultures.
The computer graphics specialist works with doctors to visualize medical conditions and surgical procedures.
She uses computer graphic digital animation to help doctors understand structures within the body of a patient.
Seeing the internal structures in a computer graphic animation on a screen is much clearer than squinting at X-rays.
Modern digital animation with computer graphics is a powerful tool for education.
As the field of computer graphics broadens, we must ask if graphics actually help students.
Research does suggest that vivid and engaging computer graphics digital imagery can be effective in the classroom.
I have a recurring dream about exams, even though I'm no longer in college.
In my dream, it's the day of my final exam and I suddenly realize I've never gone to class.
In my dream, I've never even done any of the reading assignments.
I know many other people who have the same nightmare.
Each morning, participants in the study had to write down their dream experience from the previous night.
The participants recorded if they recalled any dreams, and described each dream and its emotional intensity.
Participants then assigned each dream to a category, such as a flying dream, a bad dream, or a nightmare.
Every night while we sleep and dream, our minds are as active as when we are awake.
We dream throughout the night, in cycles of about ninety minutes each.
Images, feelings, stories, and strange combinations of characters and places can fill our dreams.
When I decided to start playing cards and gambling, things went from bad to worse.
Gambling was something I had to do, and I had already spent close to $10,000 doing it.
My friends were sick of watching me gamble my savings away.
The hardest part was the horror of leaving a casino after losing money I did not have.
Good data on the social and economic effects of legalized gambling are hard to come by.
Some studies indicate that having a casino nearby makes gambling problems more likely.
Gambling may also be associated with personal bankruptcies and marriage problems.
Over the past generation, there has been a dramatic expansion of legalized gambling.
Most states have instituted lotteries, and many have casinos as well.
Gambling has become very big but controversial business.
The wind from the hurricane shook the house, shattering a window in the kitchen.
We ran in, grabbed some food, slammed the door, and surrendered the kitchen to the hurricane.
I was afraid our house would be ripped from its foundation by the hurricane.
Later that night, with the hurricane wind shaking the house, we fell asleep huddled on the sofa.
Hurricanes can tear limbs off of trees and suck houses off their foundations.
Hurricanes dump heavy rains that can trigger floods and mudslides.
Hurricanes can also bring a storm surge: a wall of ocean water that lurches onto land.
Scientists use several methods to look for evidence of ancient hurricanes.
The strongest storms deposited layers of windblown beach sand at the bottoms of coastal lakes.
Trees drenched by passing hurricanes preserve a record of each storm in their growth rings.
American ice cream is exported around the world, but different countries have different preferences.
Many people enjoy their ice cream flavored with local delicacies.
In some tropical places, vanilla ice cream is topped with bananas and fresh mangos.
I remember making ice cream at home as a child.
We poured the cream mixture into a frozen tub, then start turning the crank to expose it to the cold.
Eventually the ice cream froze enough that I couldn't turn the hand crank any more.
Then I put the container of half-frozen ice cream into the freezer to harden.
Ice cream is a mixture of milk or cream, sugar, flavorings, and up to half whipped-in air.
The butterfat in milk and cream is what makes ice cream smooth and silky.
High-priced premium ice cream is loaded with butterfat and natural flavorings.
New ear piercings can become infected if they're not carefully cleaned.
Signs of infection include tenderness, swelling, or redness around the earlobe.
If you see these symptoms, clean the infected area and apply some ointment.
If the redness and swelling of the infection don't go away, contact your health care provider.
A local hospital has initiated new measures to reduce infections.
The local hospital has improved hand washing habits and ensured that infected patients are isolated from other patients.
The hospital has seen infection rates drop since the new measures began.
Scrubbing a wound with soap or alcohol delays healing, which increases the risk of infection.
Band-aids can increase the risk of infection by holding in heat and moisture.
Fortunately, most skin infections can easily be treated once they are diagnosed.
The reason he came to law school in the first place was cliche.
He wanted to use law to change things for the better.
He recalled one evening at law school when he and the program director had pulled an all-nighter.
They finally finished drafting a legal petition for several evicted families at sunrise.
Over the past four decades, the cost of legal education has gone up relentlessly.
Private law school tuition increased by a factor of four since the 1970s.
The market for admission to law school and for new lawyers could eventually crash.
Law school faculty often have minimal experience in actually practicing law.
Professors focus on writing law review articles for prestigious journals.
Law schools often emphasize the theoretical, with classes on topics like property law in feudal England.
When I use the riding lawnmower, the uncomfortable chair makes my back hurt.
I use the two levers in front of me to control the lawnmower.
The sharp blades underneath the lawnmower precisely sever each blade of grass.
Mowing the lawn is a long task and it has taught me patience.
A lawnmower is a machine with revolving blades that cuts grass to an even height.
The lawnmower blades may be powered by muscle or the machine may have a motor.
The most common power source for lawnmowers is a small gas engine.
Electric lawnmowers are better for the environment because they do not create emissions.
Electric lawnmowers also need less maintenance and are less expensive to run.
Electric lawn mowers use as much electricity as an ordinary toaster.
Modern opera started at the end of the sixteenth century.
Opera began as an effort to rediscover and imitate Greek tragic performance.
Early founders of opera chose tales from antiquity for their subject matter.
Later operas branched out into different sources of stories and musical traditions.
Opera is an art form in which singers and musicians perform a play that combines words and music.
Opera incorporates many of the elements of spoken theatre, such as acting, scenery, and costumes.
Performances are typically given in an opera house and accompanied by an orchestra.
The opera singer has worked hard to win the role in the new production.
The job of the opera singer is not just about singing.
Acting, stage presence, and musical interpretation of the opera singer are all critical.
But the pure, strong voice of the opera singer is certainly the star of the show.
The eagle owl is an impressive bird.
The eagle owl has ear tufts that stick up like horns.
The large orange eyes of the eagle owl are downright creepy, and look like they could pierce right through you.
This owl hunts at night, flying swiftly and silently through the darkness.
While some owl species have become endangered, others are thriving.
The barred owl has spread well beyond its previous habitat.
Early findings suggest that logging may have facilitated the invasion of the barred owl.
The owl landed on a thick branch and gripped it with her talons.
The owl pressed her wings to her sides and settled down, half-closing an eye.
The owl might have been a statue but for the glow of her eyes.
A painter must keep many elements in mind while completing a painting.
The painter has to use solid elements of design, like strong composition and lighting.
The painter has to execute the brush strokes with skill.
Most importantly, the content of the painting should reveal a glimpse of the soul of the painter.
Long ago, painters were employed more as skilled artisans than as creative artists.
However, prominent painters had the social status of scholars and members of the royal court.
Painters signed their work, decided on its subject and imagery, and established a personal relationship with their patrons.
As a painter, I learned to focus less on the actual scene and more on the painting itself.
The eye of an artist is not a camera lens that has to record everything within its field of vision in the painting.
I found nature provides useful information, but more than is needed for a good painting.
Pharmacists are increasingly involved in preventive care.
Pharmacists are becoming front-line health advisers because people go to pharmacies often.
Pharmacists are often a good source of information about public health.
Doctors consult with pharmacists because they know a lot about drug interactions and side effects.
Pharmacists dispense prescription drugs to patients and offer advice about the safe use of medications.
Pharmacists also conduct health and wellness screenings and provide vaccines.
Pharmacists must have professional degrees and pass two exams in order to be licensed.
I think the pharmacy profession chose me as much as I chose to be a pharmacist.
I was fascinated by the neatly arranged bottles in pharmacies as a child.
I know it's cliche, but I love the impact that I have on lives of my patients as their pharmacist.
It's unnerving to watch a polar bear stalk across floating sea ice.
It's even worse when you are submerged in the frigid waters directly beneath the huge polar bear.
Overhead, giant paws set down on the ice as the polar bear pursued its prey.
As part of the film crew for a polar bear documentary, I spent months capturing these shots.
Polar bears are one of the few animals that will attack people for reasons other than fear or confusion.
Polar bears may attack out of hunger because they live in a food-scarce environment.
Polar bears will sneak up on people slowly, careful to conserve their energy.
The seal is an important part of the diet of the polar bear.
When hunting, polar bears will wait by a seal breathing hole, or stalk seals that are basking on the ice.
The polar bear will crawl quietly forward and freeze in place when the seal looks around.
After climbing fifty feet up the side of the pyramid, the man gestured me into a small black entranceway.
This led into the chamber at the center of the pyramid.
I followed him down the steep, dark, narrow passage, into the pyramid.
The smell inside the pyramid was chalky and the air was thick.
More than just the tomb of the king, pyramids represented the pride of the nation.
The care that the pyramid builders took in their craft is evident.
The stones covering the pyramid were precisely fitted together and polished until the structure gleamed.
Architects are still working to solve the mysteries of how pyramids were constructed.
Some architects think ramps were built inside the walls of the pyramid to raise stone blocks.
Other architects speculate that ramps zigzagged up the exterior walls of the pyramid.
Even beginner rock climbing takes courage and strength.
Climbers who are learning rock climbing can try scrambling on large boulders.
Once rock climbers are comfortable with scrambling on large boulders, they can begin using ropes to safely climb vertical rock faces.
All of the boys on the trip were new to rock climbing.
Many of the boys were afraid of rock heights.
Having someone else check their knots and harnesses before climbing the rock helped them calm down.
The adults set up rock climbing routes appropriate for beginners.
Free-climbing is one particular style of rock climbing.
The climber relies solely on her skill and physical strength to ascend a rock face.
Rope and bolts are the only equipment used in free rock climbing
Ropes and bolts are meant only to stop the rock climber if she falls.
I hesitantly skied down the steep trail that my buddies convinced me to try.
I made a bad turn and I found myself tumbling down the ski slope.
I finally came to a stop at a flat part of the ski slope.
My skis were nowhere to be found and my poles were lodged in a snow drift up the hill.
A major strength of professional skiers is how they use ski poles.
Proper use of ski poles improves their balance and adds flair to their skiing.
It minimizes the need for upper body movements to regain lost balance while skiing.
New ski designs and stiffer boots lets skiers turn more quickly.
But faster and tighter turns increase the twisting force on the legs while skiing.
This has led to more injuries, particularly to ligaments in the knee of skiers.
Each person has his or her own response to potentially stressful situations.
One person may be devastated by unemployment, while another may find working fulltime stressful.
There are everyday stresses, like being stuck in traffic.
There are also traumatic stresses, such as divorce or loss of a child.
Some people can adapt to different levels of stress.
If not dealt with effectively, though, stress can take a real toll on health.
Remember that it's your reaction to stress that determines if it will be harmful or beneficial.
When my company was downsizing, I felt incredibly stressed and worried.
My heart would race for no reason, and I even felt dizzy at times.
Then, I started taking yoga to try to manage my stress level.
No one really knows exactly how a taste gets from your mouth to your brain.
Scientists think the process begins when a molecule of food touches a taste bud cell.
The cell carries a taste message to taste nerves beneath the cell.
It was once believed that each taste bud responded to one of the four basic tastes.
That is, a taste bud on the tip of the tongue would respond only if you were eating something sweet.
Scientists now think that a single taste bud can be sensitive to all of the basic tastes.
My sense of taste isn't very good, so I tend to eat foods with very strong flavors.
I like lots of hot sauce, and I drink my coffee with no cream, so it has a very bitter taste.
I can't even taste sweetness well, so when I make cookies I add extra sugar.
The man wore a jet black tuxedo with satin stripes.
The tuxedo was made with rich fabric cut in the latest style.
Clearly he had the tuxedo tailored, as it fit the man perfectly.
The tuxedo looked like something a professional stylist would have picked out for a formal event.
While the tuxedo is still preferred, today's grooms are making personal statements in wedding attire.
Shorter tuxedo jackets are on the cutting edge of wedding fashion for men.
Grooms are also jazzing up their tuxedos with colorful shirts and satin ties.
A tuxedo jacket is a tailless dinner jacket with black silk lapels.
Black tie trousers should be a perfect match to the tuxedo jacket.
The shirt should always be plain white and the tie should be black and match the tuxedo jacket lapels.
Cats are small furry animals with four legs and a tail.
Cats like to groom themselves by licking their fur.
Cats can hunt mice or birds, but are often fed by their owners.
The claws of cats are retractable so that they keep sharp.
Elephants are the largest kind of land mammal, weighing several tons.
An elephant has a long nose called a trunk, which can grab things or food.
The elephant has a pair of ivory tusks, for moving objects or digging into trees.
The elephant flaps its large ears to cool the blood in them and its body.
A horse is a large hoofed mammal with four long, muscular legs.
A horse has a tail and a mane on its neck, and is usually gray or brown.
Horses have been used for draft work, travel and entertainment.
A human can ride a horse while it walks, trots or gallops.
A whale is a very large mammal that lives in the ocean.
Whales breathe through blowholes on their heads when surfacing.
The blubber in a whale serves as an energy reservoir and as insulation.
Whales have been hunted for meat, whale oil and ambergris.
A blender is a kitchen appliance used to mix ingredients or puree food.
Blenders have a glass or plastic container with a rotating blade in the bottom.
Blenders are used to make milk shakes and fruit smoothies.
Blenders are also used to make cold alcoholic drinks with crushed ice.
A refrigerator is a cooling device used to contain and preserve food.
Some refrigerators can have a small compartment at freezing temperature.
A refrigerator can have shelves and small compartments for different types of food.
A refrigerator is generally white and people often put magnets on its surface.
A television is an appliance with a screen that displays moving images.
Televisions are mostly used for watching programs or films.
Televisions are used to play videogames when connected to a game console.
Television content can be broadcast or received via cable or internet.
A toaster is a kitchen appliance for toasting bread using heating elements.
Pop-up toasters toast the bread placed in a slot and eject it once done.
Toaster ovens have a door on the side, a tray within and temperature control.
Toaster ovens allow bread to be cooked with toppings like garlic or cheese.
Eagles are large birds of prey that hunt during the day and have very good eyesight.
Eagles have hooked beaks for tearing flesh, strong legs and sharp talons.
Eagles live in eyries and some species eat fish and others small mammals.
The bald eagle has a bright white head and is the national bird of the United States.
A parrot is a bird that lives in warm and tropical regions.
Parrots have brightly-colored feathers and a sharp, curved beak.
Parrots can imitate the human voice if they hear it repeatedly.
The appearance and abilities of parrots makes them popular pets.
A raven is a large black bird that thrives in many climates.
Ravens feed on carrion, insects, berries or small animals.
Ravens have large brains and are capable of problem solving.
In folklore ravens are birds of ill-omen and also tricksters.
Vultures are scavenging birds, feeding mostly on the carcasses of dead animals.
Many vultures have a bald head without feathers for losing heat.
Vultures use their large wings to soar for miles without flapping.
Vultures seldom attack healthy animals, but may kill the wounded or sick.
The eye is an organ for sensing light and coding it for the visual cortex.
Most animals have complex eyes which can detect color, motion and texture.
The fovea is the center of the human eye and the most sensitive part of it.
Insects have compound eyes made up of eye units facing in many directions.
Primates usually have four fingers and a thumb on each hand.
Fingers are used for grasping, writing, grooming and other activities.
The fingertips are sensitive to temperature, pressure and vibration.
The nail protects the tip of the finger and can be grown or decorated.
Feet are body parts at the end of a legs.
People use their feet when walking, running or standing straight.
People also use their feet to kick, in both fighting and sports.
Many cultures have rules for behavior related to feet.
The mouth is the face cavity we put food in when we eat.
The mouth has teeth to chew food and mix it with saliva.
The mouth is also used for kissing and talking.
Speech sounds are controlled by tongue placement in the mouth.
A door is a movable barrier to entrance or exit from an enclosed area.
Most doors have locks to control who gets to pass through them.
Most doors are opened by pushing or pulling a handle after they are unlocked.
Other types of doors can slide or consist of a revolving chamber.
A floor is a horizontal surface inside a building, used for walking on.
Floors may be made of bare concrete, tile, linoleum or wooden floorboards.
People often put carpets on a floor, for comfort and to dampen noise.
In buildings the floor often has pipes and electrical wiring under it.
A wall is a solid structure that defines and sometimes protects an area.
Walls delineate a building, support the roof, and divide the space into rooms.
Walls are usually made of stone, brick, or cement, as well as drywall.
Retaining walls provide a barrier to movement of earth, stone or water.
A window is a transparent opening in a wall to let light through.
A typical window is made of sheets of glass held in place by frames.
When open, a window will also let air and sound through.
Some windows have multiple panes to increase insulation inside.
A dress is a piece of clothing that women sometimes wear.
A dress is like a shirt attached to a long, matching skirt.
A dress is usually worn at formal occasions, such as a wedding or a dance.
It can be hard to climb stairs or ride a bike in a dress.
A glove is a piece of clothing that covers the hand and fingers.
Gloves to protect against cold are made of wool or lined waterproof material.
Disposable rubber or latex gloves are used to shield hands from germs or chemicals.
A mitten is a kind of glove where the four fingers are covered together.
A shoe is clothing for the foot, with a sole, an outsole and a heel.
Shoes are usually made of leather, canvas, rubber or plastic.
Women's shoes often have high heels and come in many styles and colors.
A sneaker is a shoe for sports and athletic activity.
A sweater is a heavy garment worn on the torso for warmth.
Sweaters are often knitted from wool but cotton is also common.
A sweater that opens down the front is called a cardigan.
Sweaters differ in cut, collar and sleeve shape, as well as decoration.
Drunk driving is the act of driving under the effects of alcohol.
Drunk driving of any vehicle is a crime in most of the world.
Drunk driving plays a role in almost half of all vehicle-related deaths.
Drunk drivers are caught by field sobriety and breathing tests.
Arson is the criminal act of burning a building or wildland.
A fire investigation determines if a fire was caused by accident or arson.
Arson can be done to cause damage to others or collect insurance.
The severity of the arson depends on whether people were harmed.
Murder is the unlawful killing of another human being with intent.
Murder a serious crime because it deprives the victim of their existence.
Killing in self-defense, accidentally or in war is not considered murder.
A convicted murderer is often given a life sentence or the death penalty.
Theft is the taking of person's property without their consent.
Thieves steal to own something or to sell it to receivers.
Theft is a crime and can be punishable with jail or fines.
Industrial espionage is theft of ideas and intellectual property.
A drought is a persistent shortage of the water supply caused by lack of rain.
Droughts will cause crops and plants to stop growing and die.
Extreme drought will eventually turn areas into desert and cause famine.
Large numbers of people have to migrate away from dust bowls during droughts.
Earthquakes shake the ground and can knock down buildings and other structures.
The earthquake shaking can also trigger landslides and volcanic activity.
Most earthquakes are caused by the release of energy in the Earth's crust.
An earthquake at sea can displace the seabed and cause a tsunami.
A flood is an overflow of an expanse of water that submerges inhabited land.
Flood can be caused by heavy rain or rapid snow melt, as well as earthquakes at sea.
In a flood a river will flow out of its channel or break dams and levees.
During a flood people evacuate and the contaminated water causes diseases.
A tropical cyclone is a storm formed over warm tropical sea.
Cyclones can produce very powerful winds and torrential rain.
Tropical cyclone can also cause high waves and coastal flooding.
A tropical cyclone can move inland and seriously damage property.
Coffee is made from coffee beans, the seeds of the coffee plant.
Coffee is a popular drink in many countries, and usually served hot.
Coffee contains a mild drug called caffeine that keeps people awake.
Coffee is the world's seventh-largest legal agricultural export.
Milk is a white liquid produced by female mammals to feed their young.
Newborn animals must be fed milk before they can eat solid food.
Dairy products such as cheese and butter are made from milk.
Liquid produced from soybeans and coconuts is sometimes called milk.
Orange juice is a drink made from the liquid in orange pulp.
Orange juice has a sweet, acid taste and contains a lot of vitamin C.
Freshly squeezed orange juice often contains pulp as well.
Orange juice is often drunk at breakfast from a glass.
Water is the most common liquid on Earth, covering 70% of its area.
Plants, animals and people must drink water in order to live.
Water freezes at a low temperature and becomes solid ice.
Rain is water that falls from clouds in the sky, which are condensed vapor.
An apartment is a self-contained home that is part of a building.
An apartment may have one or more rooms, as well as a kitchen and a bathroom.
Some apartments are for single people, others for families.
The apartment building can have a garage, a laundry facility or extra storage space.
A house is a permanent building or structure for people or families to live in.
A house has a roof and walls to keep out cold and rain, and windows to let light in.
A house can have rooms for purposes like sleeping, cooking or washing.
Most people leave the house to work and come back at night to eat and sleep.
An igloo is a type of shelter made from blocks of snow by Inuit.
Igloos are built in places where snow covers the land most of the time.
Igloos are often built in the shape of a dome, with an entrance tunnel.
Air pockets in snow insulate the igloo space, and body heat warms it.
A log cabin is a small house built from round logs.
Log cabin is a symbol of American frontier life and humble origins.
Log cabins were used as first shelters by european settlers.
Log cabins were built using logs with notch joints at the ends.
A cod is a fish that lives in the colder areas of the Atlantic.
Cod flesh is white and mild-tasting, and flakes easily when cooked.
Fresh cod is used for fish and chips, salted cod for elaborate dishes.
Cod has been caught, salted and traded since the time of the Vikings.
Piranhas are small, ferocious fish that live in South American rivers.
Piranhas live and attack in schools and are most active during the day.
Piranhas have very sharp teeth and are opportunistic carnivores.
Piranhas eat fish, insects, lizards, mammals and carrion.
Salmon is a fish that migrates from fresh water to the ocean and back to spawn.
Salmon flesh is orange or red and has high protein content and a nice taste.
Salmon can be eaten raw in sushi or cooked by grilling, poaching or in other ways.
Salmon is the most common farmed fish, though it can also be caught in the wild.
A shark is a large fish with a cartilage skeleton.
Sharks have streamlined bodies, with a large dorsal fin.
Most sharks predate on fish and mammals, with powerful jaws.
Sharks have very keen senses and can detect electrical fields.
An apple is a fruit that can be green, red or yellow.
Apples have thin skin, a crisp, sweet pulp and seeds inside.
Some very tart apples are used to make cider.
Apples can be eaten raw, roasted or baked in pies.
A peach is an orange-yellow fruit with a characteristic smell.
The skin of a peach is thin and covered in small, fine hairs.
Peaches have a large, red-brown stone inside which contains the seed.
Peaches are sweet and delicate, and must be harvested after ripening.
The raspberry is a fruit that grows in forest clearings or fields.
A single raspberry consists of many small fruits joined together.
Raspberries are eaten by themselves or cooked with sugar into jam.
Leaves of the raspberry are used fresh or dried in herbal teas.
A banana is a long fruit that grows in bunches, with a soft edible inside.
A banana when ripe can be yellow, purple or red and have small brown spots.
The greatest banana producers are tropical countries, such as India or Ecuador.
Unripe bananas and plantains are staple foods and often cooked like potatoes.
A chair is a piece of furniture designed for people to sit on.
Chairs consist of a seat raised above floor level, supported by legs.
Chairs can also have back and arm rests, as well as a cushion.
Seats are fixed chairs located in vehicles or in places like cinemas.
A desk is a piece of furniture used for working at, sometimes with a computer.
A desk has a flat surface and can be made of wood, plastic or metal.
A desk may have drawers to store supplies and papers.
A cubicle consists of a desk surrounded by partitions on three sides.
A bed is a piece of furniture used as a place to sleep or have sex in.
A bed is made of a mattress and a box spring, plus sheets, pillows and covers.
In waterbeds the mattress is filled with water, and in airbeds it is filled with air.
Another type of bed is the hammock, a fabric sling suspended above the ground.
A table is a piece of furniture with a flat surface and legs.
There are usually chairs around a table for people to sit.
People set cutlery, plates and food on a table to eat a meal together.
Tables are also used as surfaces to work or write on.
A boy is a young male child who has not undergone puberty.
The term boy is used to indicate sex distinctions relative to girls.
Traditionally boys like to play rough games and fight with each other.
An adult male behaving immaturely is often referred to as a boy.
A girl is a female human who has not yet reached maturity.
At puberty the body of a girl develops into that of a woman.
Girls often like playing with dolls and social games.
Girls sometimes grow long hair and wear dresses and skirts.
A man is a male human adult.
A boy becomes a man after passing through puberty.
Manhood is associated with masculinity and virility.
A man differs from a woman in height, weight, and body structure.
A woman is a female human adult.
A woman is stereotypically seen as a caregiver.
A woman can become pregnant and bear children.
A woman has different reproductive organs than a man.
A butterfly is a flying insect with four large wings.
The wings of butterflies can be very colorful and patterned.
Metamorphosis is the transformation of a caterpillar into a butterfly.
Some people collect butterflies because of their colorful wings.
Mosquitoes are thin, small flying insects that emit a high-pitched sound.
Mosquitoes have mouthparts for piercing the skin of plants and animals.
Female mosquitoes bite people and animals and suck their blood for protein.
Mosquito bites can spread yellow fever, malaria and other parasite diseases.
Spiders are insects with eight legs that make silk.
Spiders build webs with silk and use them to catch insects.
Spiders use venomous fangs to paralyse their stuck prey.
Spiders can be as small as a coin or as big as a bird.
A bee is a flying insect, with a black and yellow body and six legs.
Bees spread pollen between flowers as they collect nectar to make honey.
Bees are social insects and live together in a colony located in a hive.
Many bees have stingers and can attack if they feel threatened.
A fork is a tool for eating solid foods, with a handle and several tines.
Forks are usually  made of metal, or plastic, if disposable.
Forks are used to lift food to the mouth or to hold food in place while cutting.
Forks are used in Western cultures, and there are special kinds for various foods.
A frying pan is a small pan with sloping sides and a handle.
A frying pan is used to fry, sear and brown food.
The food is cooked on oil covering the bottom of the frying pan.
Frying pans are made of iron or teflon-clad steel.
A knife is a tool with a sharp edge that is used to cut things.
Modern knives consist of a handle and a blade, usually made of metal.
Knives have also been used as weapons and instruments in rituals.
A knife can be used to attack by slashing, stabbing or throwing.
A mug is a sturdy cup with a handle for drinking hot liquids.
A mug is normally ceramic, but can also be made of metal or glass.
A mug is thick and has a ring base for thermal insulation.
Mugs can be plain or have drawings imprinted or carved on them.
A desert is a natural environment where almost no rain falls.
Hot deserts are usually filled with sand dunes or rocks.
Some animals and plants have adapted to live in deserts.
The biggest hot desert is the Sahara in northern Africa.
A forest is an area with a high density of trees and canopy cover.
The type of forest depends on temperature and rainfall in its location.
A forest ecosystem has various types of trees and animals, as well as ground plants.
Deforestation is the cutting down of forests disregarding regeneration.
A mountain is a landform that rises steeply above surrounding land.
Mountains rise higher than hills and sometimes have snow at the top.
A range of mountains forms due to tectonic plate collision.
Mountaineers are people who climb or hike up mountains.
Swamps are low, spongy land subject to frequent inundation.
A swamp is covered with shallow water, mud and vegetation.
Swamps are nesting and breeding grounds for birds and reptiles.
Farmers often drain swamps to produce fertile arable land.
An accordion is a portable musical instrument with two keyboards.
One accordion keyboard is used for individual notes, the other for chords.
Accordions produce sound with bellows that blow air through reeds.
An accordionist plays both keyboards while opening and closing the bellows.
A clarinet is a woodwind musical instrument.
A clarinet is a long black tube with a flare at the bottom.
The clarinet player chooses notes by pressing keys and holes.
The clarinet is used both in jazz and classical music.
The piano is a popular musical instrument played by means of a keyboard.
Pressing a piano key causes a felt-tipped hammer to hit a vibrating steel string.
The piano has an enormous note range, and pedals to change the sound quality.
The piano repertoire is large and famous pianists can give solo concerts.
The violin is an instrument with four strings that is played with a bow.
Violin is the smallest and highest pitched instrument in its family.
A violinist holds the instrument between the chin and the collarbone.
Different notes are made by fingering the violin neck with one hand while bowing.
A farm is land used to grow plants or raise animals for food.
Farmers are the people who run the farm and decide what to produce.
Farms usually have a house for farmers, a silo and a barn.
A cooperative is a farm where many farmers share the land and equipment.
People go to hospitals to be healed when they are sick or injured.
Hospitals are staffed by professional physicians, surgeons, and nurses.
Some patients go to hospitals for specialist diagnosis or therapy, leaving the same day.
For some operations or treatments patients have to stay at the hospital for several weeks.
A library is a place where a collection of books, documents and media is kept.
Librarians work at libraries and are experts at finding and organizing information.
People can go to public libraries and borrow books to take home for several weeks.
Academic libraries support scholarly research and have specialized books.
A train station is a place where passengers get on or off a train.
Train stations have counters or machines for purchasing tickets.
There are waiting rooms and places to eat in a train station.
Passengers or cargo enter trains from a train station platform next to the line.
A blacksmith creates objects by forging iron or steel.
A blacksmith hammers and bends hot iron on an anvil to change its shape.
Blacksmiths wears a thick apron and handle the metal with tongs.
Blacksmiths make objects like weapons, horse shoes or iron furniture.
A carpenter is an artist or manual laborer who works with wood.
Carpenters build and repair houses, furniture, boats and other objects.
Carpenters use tools such as hammers, saws, pliers and planes.
A luthier is a carpenter that makes and repairs musical instruments.
A scientist studies and produces new knowledge about the physical world.
A scientist creates hypotheses and does experiments to test them.
Physics, chemistry and biology are classic examples of sciences.
Scientists publish their research in journals and conferences.
A soldier is a member of the national armed forces who fights on land.
A soldier in the militia must wear a uniform, usually camouflage.
In a volunteer army, a soldier is paid for his or her work.
A soldier fights using weapons such as rifles and grenades.
A hammer is a tool used to deliver an impact to an object.
A hammer is most often used to drive nails into wood.
The claw on the head of the hammer can be used to remove nails.
Hammers vary in the shape of the head and handle length.
A saw is a tool that uses a hard blade or abrasive wire to cut hard materials.
The small sharp points along the cutting side of the saw are called the teeth.
Saws can be worked by hand, or powered by an electric motor or gas engine.
Saws are used extensively in forestry, construction, carpentry and medicine.
Scissors are a two-bladed instrument used for cutting.
Scissor blades are usually metallic, with plastic or metal handles.
Depending on the size and format, scissors can cut paper, hair or fabric.
Shears are large scissors used for cutting shrubs or pieces of metal.
A screwdriver is a tool for inserting and tightening screws into something.
Screwdrivers can also be used to remove screws after they are inserted.
The screwdriver tip applies the torque from rotating the handle.
The two major types of screwdrivers are Phillips and flathead.
Broccoli is a plant in the cabbage family.
Broccoli has a green flower head and a thick, tough stalk.
Broccoli is high in vitamins, fiber and other nutrients.
Broccoli can be boiled, stir-fried or eaten raw.
Lentils are the seeds of a plant of the legume family.
Lentils can be red, green, brown, black or yellow.
Lentils are commonly used in Indian and Mediterranean cuisines.
Lentils are cooked by boiling and are a great source of protein.
Lettuce is a biennial plant often grown in temperate climates as a leaf vegetable.
Lettuce can be eaten cold and raw, in salads and other dishes, or cooked.
Lettuce is considered fairly easy to grow and a suitable crop for beginners.
Most lettuce leaves taste bitter, but some are bred to remove the bitterness.
The tomato is a shiny and smooth red fruit, with a savory taste.
A tomato softens and changes color from green to red as it gets more ripe.
Tomatoes can be used to make salads, soup, or ketchup, as well as sauce.
There are many varieties of tomatoes, with different sizes and tastes.
A bicycle is a vehicle with two wheels and pedals on a frame.
A bicycle is propelled by the pedalling of a cyclist on the saddle.
The bicycle wheels have rubber tires with an inner tube full of air.
People use bicycles for transportation, recreation and racing.
An automobile, or car, is a wheeled vehicle for transporting passengers.
A car can be powered by a gasoline or electric engine.
The driver steers the car on roads, other passengers just sit.
Cars vary in size, number of doors and the type of trunk.
A ship is a large vehicle that floats and travels on water.
A ship can be powered in the ocean by sails, steam, or diesel engines.
Ships are used to fish in the ocean and to transport cargo containers.
Cruise ships are floating hotels that take people between cities.
A train is a connected series of cars that moves between stations on a track.
The train is pulled by a locomotive, powered by diesel or electricity.
A freight train transports containers of goods or fuel over long distances.
Commuter trains transport people between suburbs and stations inside a city.
A hand grenade is an explosive used as a weapon against people.
Hand grenades are thrown and timed to explode a bit after that.
Grenades can also be fired from rifles or shoulder launchers.
Tear gas grenades are thrown into the middle of a mob to disperse it.
The axe is a tool used to split and cut wood.
The axe usually consists of a head attached to a handle.
Historically, axe heads were made of stone and then metal.
Axes are used by woodcutters and firemen entering buildings.
A rifle is a firearm that rests on the shoulder and has a barrel with twisting grooves.
The grooves make the bullets spin around the rifle axis as they fly through the air.
Rifles are used in hunting and shooting sports, sometimes with scopes.
Assault rifles can fire in bursts and are the standard infantry weapon.
Spears are weapons that consist of a pole and sharpened head at one end.
Spears were the most common personal weapon before the advent of firearms.
Spears were used for stabbing or throwing when fighting in war.
Some native people still use the spear for hunting and fishing.
