LESSON: Engineering Better Blades GRADE: 4 SUMMARY:

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1 LESSON: GRADE: 4 SUMMARY: Working in groups, students will design mini wind turbine blades from recycled materials, and measure the energy generated. After each trial, they will refine their design and test it again. Finally, groups will share their results with the class and draw conclusions about the best blade. OBJECTIVES- Iowa Core: Energy 4-PS3-4 Apply scientific ideas to design, test, and refine a device that converts energy from one form to another. Earth and Human Activity 4-ESS3-1 Obtain and combine information to describe that energy and fuels are derived from natural resources and their uses affect the environment. Engineering Design 3-5-ETS1-1 Define a simple design problem reflecting a need or want that includes specified criteria for success and constraints on materials, time, or cost. 3-5-ETS1-2 Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem. 3-5-ETS1-3 Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved. 1

2 MATERIALS & RESOURCES: Per group KidWind MINI wind turbine, without red blades* MINI wind turbine hub* Digital multimeter* Red and black alligator clips* ¼ x 5 dowels* Scissors* Tape* Recycled cardboard boxes, paper, plastic* thin cardboard like cereal boxes is easiest to cut A windy day, or box fan or clip fan* Observations of wind speed See Teachers Going Green Power of the Wind 3 rd grade, or PBS s How Windy Is It? Photos of Iowa wind turbines* See KidWind s Powerpoint: Wind Power for Students for ideas * Materials for this lesson can be found in the TGG Wind Energy Kit. shellyjohnson010@gmail.com for checkout information. PRESENTATION: Students task will be to design better wind turbine blades. Iowa is a major producer of wind energy. One of the ways we can Keep Iowa Beautiful is by reducing fossil fuel use. We see Iowans doing this every time we drive across the state and see the many wind farms. Have you ever noticed the design they use? Wind turbines have come a long way from pinwheels or small windmills farms once used to run water pumps, and the blades play a vital role in catching the wind which will be converted to mechanical energy. Today students will be challenged to design blades that use the fewest amount of materials while producing the most electrical energy. 2

3 DIRECTIONS: 1. Examine photos of wind turbines. Why is the blade design important? What factors help us determine which blades are best? 2. Define the problem: You are a wind turbine engineer. Your task is to design better blades for this wind turbine. When you are finished, you should be able to describe the characteristics of a blade that produces the most electrical current. See Which Blades are Best? at for detailed instructions designing wind blades with the engineering design process. Their steps have been adapted below. 3. Design: Groups of 3-5 students will discuss and draw various blade designs, discussing advantages and challenges, and come to a consensus on their blade trial. 4. Build: Students will create their design using recycled materials and tape it on a dowel. The screw on the black hub can be loosened so dowels can be inserted with blades. Students should record information about their blades such as the shape, number of blades, and blade pitch (the angle of the blades with respect to the plane of rotation). 5. Test: The hub should be attached to the turbine and tested either outside on a windy day or in front of a fan. Hint: placing the wind turbine about inches from the fan seems to work well. Students should attach the multimeter to their wind turbine, measure the voltage at the 20V setting, and record their data (typically between 1-4 volts). Caution: Do not stand in the plane of rotation of the blades. Wear safety glasses while blades are spinning. 3

4 6. Refine: Students reflect on their blade design and look for improvements. Brainstorm blade variables. A variable is something that can be changed. Variables may include blade length, number of blades, blade angle, blade shape, blade material. How could changing one variable affect the electric energy produced? Emphasize the importance of changing just one variable. Note: Blade pitch significantly affects the amount of drag on the blades. Changing this variable may have dramatic results for groups. Likewise, changing the blade pitch along with other variables will create problematic results. Keeping in mind these options, groups should choose a variable to refine and then retest their wind turbine, as much as time permits. 7. Present: Each group should share with the class their data including blade design and their results. 8. Reflection: Your task was to be a wind turbine engineer creating the best blades. Please make a list of your recommendations of how to create a wind turbine transferring the most wind energy to electrical energy, at the lowest cost. 4

5 REFLECTION QUESTIONS: WHAT HAPPENED? Describe the energy conversions that took place in your tests today. Groups made changes to blade shape, number, pitch, and other variables. Which had the greatest impact on the volts produced? How did your group work together well? How could your collaboration improve? SO WHAT? What did you learn about design today? How does working with a group help when working through the engineering design process? NOW WHAT? How has your thinking changed after this experiment? What will you do differently when working with a group? TIME: 90 min. 5