Objective
the students will create a 'propeller' given a piece of paper and a paper clip as well as their knowledge of how propellers move.
Materials
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a table fan or standing fan
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paper
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scissors
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paper clips
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student Science Journals
Procedure
Introduction: Set a table fan in view of the classroom at the beginning of the lesson. For this lesson, the students should already understand about the four basic concepts of flight: weight, lift, thrust, and drag. Ask the students the different ways in which a plane can move forward through the air. They will give answers such as propellers and jet engines, both are correct. Ask the students to describe what a propeller looks like and how they think it works to move a plane. A student should, at some point, notice the fan and say that a propeller looks (and works) just like a fan with its rotating blades. Turn on the fan and make sure all the students get a chance to feel how the air is sucked in the back and pushed out the front, try to get the students to use these words themselves to describe how the fan is working.
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1. Distribute a piece of paper, scissors, and a paper clip to each student (or to pairs of students). Tell the students they will be making their own propellers of sorts, that what they will be making should simulate the shape and spiraling action of a propeller but not necessarily be able to pull a plane forward.
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2. Set a time and allow the students to work on their designs. Give them enough time to work on their designs, complete at least three test runs, and record their observations in their journals. There are several designs that will work. However, if none of the students create working propellers, have one already made to show the class to help them along. It should have two 'arms' reaching up, and one arm reaching down. Bend each arm at the top at a 90 degree angle, in opposite directions, attach the paper clip to the bottom arm. Hold the paper at the place where the two top arms are bent and let go, the devise should slowly spiral to the ground.
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3. Once the students have the general shape of the propeller, have them begin experimenting by slightly twisting the arms at the top, or bending the edges in different ways, adding on or taking away paper clips.
Closure: Discuss what made the paper propellers spin as they floated to the earth. Also, discuss how a plane needs thrust to move through the air, and that a plane is actually pulled through the air rather than pushed. The propeller blades on a small plane move air in such a way that the air is pulled through the propellers and pushed out the back of them, the same way that a fan works.
Extension: Try to create a way to reduce friction enough on a small table fan so that it can actually be pulled along a table or the floor. Very smooth rolling wheels (such as inline skate wheels, or desk chair wheels) can be fastened to the bottom of the fan and place it on a table or the floor covered with some material that is smooth (a glossy paper or contact paper). The students will be able to see more clearly the action of pulling rather than pushing.