1. We should never put anything in or near our eyes, unless we have a reason to use eye drops. We would only do that if our doctor or parent told us to use them.
2. If the lens in our eye doesn’t work quite right, we can get glasses to help us see. Glasses have lenses in them that work with our eye’s own lens to help us see better.
3. Just behind the pupil is a lens. It is round and flat. It is thicker toward the middle.
4. Over the front of our eye is a clear covering called the “conjunctiva.”
5. Blinking helps to wash tears over our eyeballs. That keeps them clean and moist. Also, if something is about to hit our eye, we will blink automatically.
6. Some people start to sneeze if they are exposed to sunlight or have a light shined into their eye.
7. The highest recorded speed of a sneeze is 165 km per hour.
8. Our eyes have many parts. The black part on the front of our eye is called the “pupil.” It is really a little hole that opens into the back part of our eyes.
9. Our body has some natural protection for our eyes. Our eyelashes help to keep dirt out of our eyes. Our eyebrows are made to keep sweat from running into our eyes.
10. The most common injury caused by cosmetics is to the eye by a mascara wand.
11. It is impossible to sneeze with your eyes open.
12. Around the pupil is a colored muscle called the “iris.” Our eyes may be BLUE, BROWN, GREEN, GRAY OR BLACK, because that is the color of the iris.
13. Our eyes are very important to us, and we must protect them. We don’t want dirt, sand, splinters or even fingers to get in our eyes.
14. The reason why your nose gets runny when you are crying is because the tears from the eyes drain into the nose.
15. The space between your eyebrows is called the Glabella.
16. The white part of our eye is called the “sclera.” At the front, the sclera becomes clear and is called the “cornea.”
17. We don’t want our eyes to get scratched or poked. That could damage our sight!
18. Babies’ eyes do not produce tears until the baby is approximately six to eight weeks old.
19. Inside our eye, at the back, is a part called the “retina.” On the retina are cells called “rods” and “cones.” These rods and cones help us to see colors and light.
20. Your eyes blinks over 10,000,000 times a year!
21. The study of the iris of the eye is called iridology.
22. The shark cornea has been used in eye surgery, since its cornea is similar to a human cornea.
23. The number one cause of blindness in adults in the United States is diabetes.
24. The eyeball of a human weighs approximately 28 grams.
25. The eye of a human can distinguish 500 shades of the gray.
26. The cornea is the only living tissue in the human body that does not contain any blood vessels.
27. The conjunctiva is a membrane that covers the human eye.
28. Sailors once thought that wearing a gold earring would improve their eyesight.
29. Research has indicated that a tie that is on too tight cam increase the risk of glaucoma in men.
30. People generally read 25% slower from a computer screen compared to paper.
31. Men are able to read fine print better than women can.
32. In the United States, approximately 25,000 eye injuries occur that result in the person becoming totally blind.
33. All babies are colour blind when they are born.
34. A human eyeball weighs an ounce.
Air is a mixture of gases that circle Earth, kept in place by gravity. Air makes up Earth’s atmosphere. The air we breathe is 78 percent nitrogen gas, 21 percent oxygen, 0.9 percent argon, and 0.03 percent carbon dioxide, along with water vapor (floating molecules of water).
Also present are traces of other gases and tiny bits of dust, pollen grains from plants, and other solid particles. As our atmosphere extends higher and higher above Earth, toward outer space, air becomes thinner and the combination of gases in the air changes.
Today’s computers contain millions of transistors placed in a tiny piece of sili- 162 con, some so tiny that they can fit in an ant’s mouth. The transistors (devices that control the flow of electric current) are packed and interconnected in layers beneath the surface of the chip, which is used to make electrical connections to other devices. There is a grid of thin metallic wires on the surface of the chip.
This silicon chip was independently co-invented by two American electrical engineers, Jack Kilby and Robert Noyce, in 1958–1959. The chip, along with the invention of the microprocessor, allowed computers to get smaller and more efficient. Silicon chips are also used in calculators, microwave ovens, automobile radios, and video cassette recorders (VCRs).
James Spangler, a janitor at an Ohio department store who suffered from asthma, invented his “electric suction-sweeper,” in 1907 as way of picking up the dust and debris that triggered his health condition. His invention was the first practical domestic vacuum cleaner. It used an electric fan to generate suction, rotating brushes to loosen dirt, a pillowcase for a filter, and a broomstick for a handle.
Because it was heavy and hard to handle, Spangler sold the rights of his invention to his relative, William Hoover, whose redesign of the appliance coincided with the development of the small, high-speed universal motor, in which the same current (either AC or DC) passes through the appliance’s rotor and stator. This gave the vacuum cleaner more horsepower, higher airflow and suction, better engine cooling, and more portability than was possible with the larger, heavier induction motor. Hoover’s model has since been refined, but the mechanics of his vacuum cleaner are still used in vacuum cleaners today.
Many volcanoes occur near the area where two ridges or plates of Earth’s crust meet. Circling the Pacific Ocean—where crust plates meet—is a group of volcanoes known as the Ring of Fire. Plate movement in such regions may allow liquid rock, called magma (it’s called “lava” only after it rises to the surface), that is located in chambers in Earth’s interior to rise, resulting in volcanic activity. (Such conditions often result in earthquakes as well.)
Volcanic activity can take place under the ocean as well as on land, and when this happens the formation of islands sometimes results.
Airplanes function according to a complex mix of aerodynamic principles—theories that explain the motion of air and the actions of bodies moving through that air. Airplanes get their power from engines. Small planes generally use piston engines, Which turn propellers that push aircraft through the air in the same way that boat propellers push vessels through water. But bigger planes use jet engines, powered by burning fuel. These engines expel great amounts of air that thrust a plane forward and up. An airplane must be in constant motion—its wings slicing through rushing air to create lift—in order to stay up; moving air is also required to steer it. In order to get enough lift to rise into the air on takeoff, an airplane has to travel along the ground first at great speed.
Airplanes are able to lift into the air and stay there because of the shape of their wings. An airplane wing is flat on the bottom and curved on the top. When a plane’s engines push it forward, air divides to travel around its wings. The air that passes over the larger curved top moves faster than the air that passes under the flat bottom. The faster-moving air on top becomes thinner and has lower pressure than the air below, which pushes the wing up. Uneven air pressure caused by the shape of an airplane’s wings, then, creates a force called lift, which allows an aircraft to fly.
The femur, or thighbone, is the biggest bone in the body. The average femur is 18 inches (45.72 centimeters) long. The longest bone ever recorded was 29.9 inches (75.95 centimeters) long. It was from an 8-foot-tall (2.45 meters) German who died in 1902 in Belgium.
The stirrup (also called the stapes) in the middle ear is the smallest bone in the body. A tiny, U-shaped bone that passes vibrations from the stirrup to the cochlea, it weighs about 0.0004 ounces (0.011 grams) and can measure just one-tenth of an inch.
Green plants get nourishment through a chemical process called photosynthesis, Which uses sunlight, carbon dioxide, and water to make simple sugars. Those simple sugars are then changed into starches, proteins, or fats, which give a plant all the energy it needs to perform life processes and to grow. Generally, sunlight (along with carbon dioxide) enters through the surface of a plant’s leaves. The sunlight and carbon dioxide travel to special food-making cells (palisade) deeper in the leaves. Each of these cells contain a green substance called chlorophyll.
Chlorophyll gives plants their green color and traps light energy, allowing food making to take place. Also located in the middle layer of leaves are special cells that make up a plant’s “transportation” systems. Tubelike bundles of cells called xylem tissue carry water and minerals throughout a plant, from its roots to its outermost leaves. Phloem cells, on the other hand, transport the plant’s food supply sugar dissolved in water—from its manufacturing site in leaves to all other cells.
Although a helicopter doesn’t have wings like an airplane, it uses the same principle of lift to rise and maneuver in the air. The blades of a helicopter’s propeller-like top rotor are shaped just like a plane’s wings—flat on the bottom and rounded on the top—and are likewise adjustable. Instead of rushing forward through the air like a plane does to gather enough lift to fly, a helicopter moves only its (three to six) rotor blades, which are attached to a central shaft driven by an engine.
The rotor blades slice through enough air—creating the changes in surrounding air pressure that produce lift—to achieve flight. Adjusting the angle at which the rotor blades are set helps control a helicopter’s lift and manner of flight. Because the angle of the rotor is adjustable, too, a helicopter has far greater maneuverability than an airplane: besides moving up, down, and forward, it can fly backward and hover in the air.
There is no such thing as “earthquake season.” Earthquakes happen in cold weather, hot weather, dry weather, and rainy weather. Weather, which takes place above Earth’s surface, does not affect the forces several miles beneath the surface, where earthquakes originate.
The changes in air pressure that are related to the weather are very small compared to the forces in Earth’s crust, and the effect of air pressure does not reach beneath the soil.