TASK DEFINITION: Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
PROBLEM: Microscopes, tools that you may get to use in your class, are some of the most important tools in biology ( Figure Microscopy is the study of small objects using microscopes. Look at your fingertips. Before microscopes were invented in 1595, the smallest things you could see on yourself were the tiny lines in your skin. But what else is hidden in your skin? Over four hundred years ago, two Dutch spectacle makers, Zaccharias Janssen and his son Hans, were experimenting with several lenses in a tube. They discovered that nearby objects appeared greatly enlarged, or magnified. This was the forerunner of the compound microscope and of the telescope. In 1665, Robert Hooke, an English natural scientist, used a microscope to zoom in on a piece of cork - the stuff that makes up the stoppers in wine bottles, which is made from tree bark. Inside of cork, he discovered tiny structures, which he called cells. It turns out that cells are the smallest structural unit of living organisms. This finding eventually led to the development of the theory that all living things are made of cells. Without microscopes, this discovery would not have been possible, and the cell theory would not have been developed. Hookes discovery of the cell set the stage for other scientists to discover other types of organisms. After Hooke, the "father of microscopy," Dutch scientist Antoine van Leeuwenhoek ( Figure 1.2) taught himself to make one of the first microscopes. In one of his early experiments, van Leeuwenhoek took a sample of scum from his own teeth and used his microscope to discover bacteria, the smallest living organism on the planet. Using microscopes, van Leeuwenhoek also discovered one-celled protists and sperm cells. Today, microscopes are used by all types of scientists, including cell biologists, microbiologists, virologists, forensic scientists, entomologists, taxonomists, and many other types. Antoine van Leeuwenhoek, a Dutch cloth merchant with a passion for microscopy. Some modern microscopes use light, as Hookes and van Leeuwenhoeks did. Others may use electron beams or sound waves. Researchers now use these four types of microscopes: 1. Light microscopes allow biologists to see small details of a specimen. Most of the microscopes used in schools and laboratories are light microscopes. Light microscopes use lenses, typically made of glass or plastic, to focus light either into the eye, a camera, or some other light detector. The most powerful light microscopes can make images up to 2,000 times larger. 2. Transmission electron microscopes (TEM) focus a beam of electrons through an object and can make an image up to two million times bigger, with a very clear image. 3. Scanning electron microscopes (SEM) allow scientists to find the shape and surface texture of extremely small objects, including a paperclip, a bedbug, or even an atom. These microscopes slide a beam of electrons across the surface of a specimen, producing detailed maps of the surface of objects. Magnification in a SEM can be controlled over a range from about 10 to 500,000 times. 4. Scanning acoustic microscopes use sound waves to scan a specimen. These microscopes are useful in biology and medical research. Scanning Electron Microscope at (5:04) Click image to the left or use the URL below. URL: 1. How is the electron beam focused? 2. What part of a specimen does a scanning electron microscope look at? 3. Why is it important that a specimen for an electron microscope be placed in a vacuum? Why is this step unnecessary for a light microscope?

SOLUTION: who discovered single-celled protists?

PROBLEM: An Australian inventor has designed and built an environmentally friendly ferry that uses solar and wind power to transport people around Sydney Harbor. Robert Dane and his Solar Sailor were given the top prize at the Australian Design Awards recently. The Solar Sailor has been in use for six months. It uses four sources of energy for its power -- solar, wind, battery power with stored solar energy and a fuel generator in store all controlled by computers. The ferry can travel up to 7.5 knots on just wind and solar power. It's solar wings and fiberglass solar panels which not only take in sunlight and store it in batteries, but also act as sails. "We angle our solar panels to the sun in two planes , which increases the amount of energy we get from the sun by 40 percent," Dane says. "And also we can use that same structure to do another job, which is also the sail, and so these wing sails actually push the ferry forward just like a soft sail does." Computers check the sun and wind and angle the solar wings to take in the most sunlight. If there isn't much wind or it is a cloudy day, energy stored in the batteries runs the electric motor for up to five hours. "If the batteries are too low, then the computer turns the generator on so the boat is always able to meet a commercial schedule, or get from point A to point B no matter what," Dan explains. Dane got his idea for the Solar Sailor from a book on insects. He was amazed how insects use their wings to collect solar energy to warm themselves. "When I read that, I realized there was a good example in nature for what we were going to do, which was to use a solar wing to collect solar energy and also to sail," he says.

SOLUTION: What is the Solar Sailor?

PROBLEM: In physics, resistance is opposition to the flow of electric charges in an electric current as it travels through matter. The SI unit for resistance is the ohm. Resistance occurs because moving electrons in current bump into atoms of matter. Resistance reduces the amount of electrical energy that is transferred through matter. Thats because some of the electrical energy is absorbed by the atoms and changed to other forms of energy, such as heat. Q: In the rugby analogy to resistance in physics, what do the players on each team represent? A: The player on the blue and black team represents a moving electron in an electric current. The players on the red and blue team represent particles of matter through which the current is flowing. How much resistance a material has depends on several factors: the type of material, its width, its length, and its temperature. All materials have some resistance, but certain materials resist the flow of electric current more or less than other materials do. Materials such as plastics have high resistance to electric current. They are called electric insulators. Materials such as metals have low resistance to electric current. They are called electric conductors. A wide wire has less resistance than a narrow wire of the same material. Electricity flowing through a wire is like water flowing through a hose. More water can flow through a wide hose than a narrow hose. In a similar way, more current can flow through a wide wire than a narrow wire. A longer wire has more resistance than a shorter wire. Current must travel farther through a longer wire, so there are more chances for it to collide with particles of matter. A cooler wire has less resistance than a warmer wire. Cooler particles have less kinetic energy, so they move more slowly. Therefore, they are less likely to collide with moving electrons in current. Materials called superconductors have virtually no resistance when they are cooled to extremely low temperatures. Resistance can be helpful or just a drain on electrical energy. If the aim is to transmit electric current through a wire from one place to another, then resistance is a drawback. It reduces the amount of electrical energy that is transmitted because some of the current is absorbed by particles of matter. On the other hand, if the aim is to use electricity to produce heat or light, then resistance is useful. When particles of matter absorb electrical energy, they change it to heat or light. For example, when electric current flows through the tungsten wire inside an incandescent light bulb like the one in the Figure 1.1, the tungsten resists the flow of electric charge. It absorbs electrical energy and converts some of it to light and heat. Q: The tungsten wire inside a light bulb is extremely thin. How does this help it do its job? A: The extremely thin wire has more resistance than a wider wire would. This helps the wire resist electric current and change it to light.

SOLUTION:
the si unit for electric resistance is the