You couldnt survive without your skin. It has many important functions. The main function of the skin is controlling what enters and leaves the body. It prevents the loss of too much water from the body. It also prevents bacteria and other microorganisms from entering the body. The skin helps maintain a constant body temperature. It keeps the body cool in two ways. Sweat from sweat glands in the skin evaporates to cool the body. Blood vessels in the skin dilate, or widen. This action increases blood flow to the body surface. This allows more heat to reach the surface. The heat is then able to radiate off the body. The opposite happens to retain body heat. Blood vessels in the skin constrict, or narrow. This decreases blood flow to the body surface. This reduces the amount of heat that reaches the surface. When this happens, less heat can be lost to the air.

Question: "What happens when less heat reaches the surface of your skin?"

OPTIONS:
- no
- yes

Answer: "Got stroke"

Response: no

Surely, you have noticed the tall poles along the roadside. Do you know what is on top of those poles? Thats right, wires that carry electric current. These wires carry electric current to your home. But what is electric current? Electric current is actually the flow of electrons. You may recall, an electron is the outer-most particle in an atom. They have a negative charge. Electricity is the continuous flow of these particles. Electrons are able to move through wires. Their speed can even be measured. The SI unit for electric current (or speed) is the ampere (A). Ampere is often shortened to amp. Electric current may flow in just one direction, or it may keep reversing direction. Direct current (DC) flows in only one direction. Direct current is what is used in devices like flashlights. Alternating current (AC) flows in two directions. This is the type of current that flows into your home through wires.

Question: "How many directions is the current flowing in that arrives through wires into our homes?"

OPTIONS:
- no
- yes

Answer: "Two"

Response: yes

Bin Laden and his aides did not need a very large sum to finance their planned attack on America. The 9/11 plotters eventually spent somewhere between $400,000 and $500,000 to plan and conduct their attack. Consistent with the importance of the project, al Qaeda funded the plotters. KSM provided his operatives with nearly all the money they needed to travel to the United States, train, and live. The plotters' tradecraft was not especially sophisticated, but it was good enough. They moved, stored, and spent their money in ordinary ways, easily defeating the detection mechanisms in place at the time. The origin of the funds remains unknown, although we have a general idea of how al Qaeda financed itself during the period leading up to 9/11. General Financing As we explained in chapter 2, Bin Laden did not fund al Qaeda through a personal fortune and a network of businesses in Sudan. Instead, al Qaeda relied primarily on a fund-raising network developed over time. The CIA now estimates that it cost al Qaeda about $30 million per year to sustain its activities before 9/11 and that this money was raised almost entirely through donations. For many years, the United States thought Bin Laden financed al Qaeda's expenses through a vast personal inheritance. Bin Laden purportedly inherited approximately $300 million when his father died, and was rumored to have had access to these funds to wage jihad while in Sudan and Afghanistan and to secure his leadership position in al Qaeda. In early 2000, the U.S. government discovered a different reality: roughly from 1970 through 1994, Bin Laden received about $1 million per year-a significant sum, to be sure, but not a $300 million fortune that could be used to fund jihad. Then, as part of a Saudi government crackdown early in the 1990s, the Bin Laden family was forced to find a buyer for Usama's share of the family company in 1994. The Saudi government subsequently froze the proceeds of the sale. This action had the effect of divesting Bin Laden of what otherwise might indeed have been a large fortune. Nor were Bin Laden's assets in Sudan a source of money for al Qaeda. When Bin Laden lived in Sudan from 1991 to 1996, he owned a number of businesses and other assets.

Question: "How did Bin Laden fund the attack against America?"

OPTIONS:
- no
- yes

Answer: "Al Qaeda funded the plotters"

Response: yes

You might want to know how cold it is. You may need to know how fast the wind is blowing. Maybe it rained last night? Do you know how much? Does it feel humid to you? You have heard all these questions before. To answer these questions, we need data. That data comes from special tools. These tools collect data about the weather. You can see some of the common tools listed below: A thermometer measures temperature. An anemometer measures wind speed. A rain gauge measures the amount of rain. A hygrometer measures humidity. A wind vane shows wind direction. A snow gauge measures the amount of snow.

Question: "How can you measure the direction and velocity of the wind?"

OPTIONS:
- no
- yes

Answer: "Rain gauge"

Response:
no