ancestors- family members who lived before you. Parents, grandparents and great grandparents are ancestors.

centuries - periods of l00 years. When talking of a specific century, one adds a number - for example, the date 1544 is in the 16th century.

commercially successful - made money. If you have a hot dog stand that is commercially successful, you make money at the end of the day when you have finished selling hot dogs.

continent - land mass. One of seven great divisions of land on the globe which is divided into countries. Australia and North America are continents.

locks -machines or devices that raise or lower a ship in water so that it can go from one level of water to another. The locks of the canal let the ship cross from East to West.

reliable - trustworthy. A map is a reliable way to find a way to get to Disneyland.

strait - a comparatively narrow passageway connecting two large bodies of water. The Bering Strait connects the Bering Sea and the Artic Ocean.

travois - A travois was like a sledge, it had two poles which were fastened to a person, a dog or a horse. Cloth was wrapped around the poles and goods or people were placed on the cloth which was then dragged by whomever had the poles placed on him.

tribe - a social group made of many family members. The Apache tribe claimed the Southwest as its territory.