A tornado drill is something people do to practice what they would do if there were a tornado. It is usually done in a building such as a school or office. It starts with a signal such as an alarm or a spoken message over an intercom. After they hear the signal, people in the building go to a certain part of the building. This is usually a room deep inside the building (probably near the middle), or a hallway with no windows. They then get into a safe position. This might include kneeling on the ground with their hands over their heads.