Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: Bacteria are so small that they can only be seen with a microscope. When viewed under the microscope, they have three distinct shapes ( Figure below ). Bacteria can be identified and classified by their shape:. Answer: by their shape

Answer: How are bacteria identified and classified?

Question: Passage: The global pattern of precipitation is influenced by movements of air masses. For example, there is a global belt of dry air masses and low precipitation at about 30 N and 30 S latitude. Answer: air masses

Answer: The global pattern of precipitation is influenced by movements of what?

Question: Passage: Imagine the thrill of riding on a roller coaster like this one! The coaster slowly crawls to the top of the track and then flies down the other side. It also zooms around twists and turns at breakneck speeds. These changes in speed and direction are what make a roller coaster ride so exciting. Changes in speed or direction are called acceleration. Answer: acceleration

Answer:
What is the term for changes in speed or direction, changes that make a roller coaster ride so exciting?