What term refers to a guess about what will happen next?

The term that best fits the description of a guess about what will happen next is "prediction." A prediction is specifically founded on available information or patterns observed in data, which leads one to suggest a possible outcome in the future. This term is commonly used in various fields, including science, statistics, and everyday language, to indicate an informed estimate of what is likely to occur based on existing knowledge.

In contrast, an assumption generally refers to something accepted as true without proof, rather than a forecast of an event. A theory involves a well-substantiated explanation of an aspect of the natural world, grounded in a body of evidence, and does not merely guess future occurrences. Finally, a conclusion is a statement that follows logically from the information presented, often derived after considering evidence, rather than projecting what will happen next.