What safety precautions do you need to take so that you will be safe during a tornado?

The first safety precaution you need to take during a tornado is to have the weather channel on loud or have a weather radio so that you know when the storm is coming, how severe it is, and when it is ending. The second precaution is to hide in a room with no windows so that the tornadoes air pressure doesn't break the glass. Another precaution would be to put a mattress ontop of your body. You don't neccessarily have to put a mattress on your head, just anything that would protect you from falling objects or materials that the tornado may make. Also if you have a tornado shelter then you have an obvious answer to this question.

If you are in a car and you somehow figure out that a tornado is coming then you can take these basic precautions. First you pull over if you are in a rural area. Then you find a secluded area or a ditch that you can lay down in until it is over. Also if you can find cushiony materials where you are, or have some in your car bring them with you. Whatever material you find bring it with you and protect yourself. One of the biggest mistakes you can make is trying to beat the tornado in a car race. Some tornadoes can travel up to 100 mph.
If you are in the city during a tornado follow these safety procedures. Find a safe place (if possible) to park your car. Find the nearest biggest building in town. Also metallic structures are much more study than wooden structures. Go into a small room secluded with no windows. If others do not know of the tornadoes presence then tell them. Keep someone constantly monitoring the weather channel. Most importantly, be patient and wait until you know the storm has ended.

What is a Fujita scale and what does it represent?

The Fujita scale , or F-scale, is a measurement scale to determine how severe they are. The bigger the number the more damage and devastation they will cause. The number is officially determined by the meteorologist or someone else that has a college degree in weather. They determine this number after they see what damage a tornado has done to buildings trees and what not.

But they don't just see how many trees it toppled over, or how many buildings collapsed, they observe what types of buildings were damaged. Because an F-6 tornado may have overturned a solid steel plated building, versus an F-O tornado that overturned a shack. If the tornado made damages to buildings made of stronger materials and uprooted trees then it would be generally a stronger tornado. But if a tornado had almost no effect on an environment then it would be an F-O.
The Fujita scale was introduced in 1971 by Ted Fujita (University Chicago) who made the scale with Allan Peterson head of the N.S.S.F.C. It stands for the National Severe Storms Forecast Center. The Fuita scale only goes up to the number 6, and the minimum number is O. Many tornadoes are measured at level zero and commonly don't even touch down. But thankfully the meteorologists have never measured an F-6. These are the basics of the Fujita Scale. (http://en.wikipedia.org/wiki/Fujita_scale)

What causes the formation of tornadoes?

Tornados are formed when hot, moist air meets cold, dry air. When these opposite air properties combine they make a supercell thunderstorm. The part of the supercell thunderstorm that a tornado forms in is called a mesocyclone. Another requirement for tornados to form is an unstable atmosphere. When the wam air rises it creates an updraft which mixes with the heavier cold air. This finally makes the wind spin in a circular or cyclonic motion making a tornado happen.
The directional change in wind is known as the wind sheer. When winds develop more the faster they rotate. When they rotate faster they also become more compact which contributes to making the air around the tornado have very low pressure. It also contributes to the air's instability and helps the likelihood that the tornado will be devastating.

All of these factors help tornados form, and some of them enhance the power of the storm. But you always have to have a preexisting thunderstorm to start a tornado. One sign of a tornado forming is an anvil-looking cloud that is located in the eye of the storm. And even if a tornado forms there still is a chance that it won't touch ground, which means that everyone has paniced over nothing! That, is how tornados form. ( http://www.nssl.noaa.gov/edu/safety/tornadoguide.html)