9781422275146

WORDS TO UNDERSTAND

composite material : a substance made of two or more materials that, when combined, has different chemical or physical properties from the original substances Global Positioning System (GPS) : a satellite-based navigation system established by the U.S. Department of Defense that is made up of at least twenty-four satellites; most drones have a built-in GPS system that allows pilots to track their position/ location, while an autonomous drone uses GPS to navigate as it conducts missions poachers : people who engage in the illegal hunting, capturing, and killing of wild animals—for entertainment or profit UNESCO Heritage Site : a place designated by the United Nations Educational, Scientific and Cultural Organization (UNESCO) as having special cultural or physical importance, such as Yellowstone National Park in the U.S., the Acropolis in Greece, and the Taj Mahal in India

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