Explain to students that you are going to project a short story on the overhead, and read it to them as they read along. Show and read the first story. When it is solved, ask the class what their false assumption was. An example of this might be the assumption that the sun moves around the earth, resulting in the construction of complex orbits of planets and moons to explain their observed motions, all based on an earth-centered system. Proposing that the sun might be at the center enabled early astronomers to construct much simpler orbits.
Similar stories exist for the assumed causes of disease, behaviors, weather, etc.
Point out that one of the strategies of science is to recognize how easy it is to make false assumptions about the workings of nature, and to devise methods for avoiding or revealing those false assumptions for what they are. There is a cabin on the side of a mountain. Three people are inside and they are dead. They died in an airplane crash. Actually, it is the cabin of a 747 jetliner.