Excerpt from “The Relative Motion of the Earth, Moon, and Sun” Lesson Plan
o Write on the board: “Relative Motion” and “Motion of the Earth, Moon, and Sun”. o Begin by telling the class that you are going to “blow a hole in what they know” and fill it with new knowledge. Explain “there are some things in science you probably think you know, but you don’t know everything.” Ask, with a show of hands, “Who knows how the Sun, Earth and Moon move?” o Ask a volunteer to draw on the board the motions of the Sun, Earth, and Moon. o They will probably draw a diagram that looks similar to this: [pic]
Remind the students that these “paths” are called orbits, they are a result of gravitational pull and orbital velocity, and all of the orbits are counterclockwise. o Explain that this diagram is one way to think about the motion of the Sun, Earth, and Moon, and it is not wrong, but this diagram does not tell the entire story. Relative Motion
o Discuss relative motion. How do we know that something is moving? Show video disc of two trains and a man walking on a boat close to shore. Write on the board “All motion is relative to whatever frame of reference is chosen, because there is no motionless frame.” Discuss, asking the following questions: 1) What is a frame of reference? (A frame of reference is a set of reference points with respect to which motion is measured. These points move together and keep their relative distances and angles of view. Examples include interior of a house, a ship, airplane, car, railcar, spaceship, surface of the Earth, a moving elevator, a river carrying a swimmer) 2) Why is there no motionless frame? (There is nothing in the Universe that is not moving) 3) What frame of reference do we usually use when we are describing motion? (We use the surface of the Earth.) Give the following example where we have 2 different frames of reference:...
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