Target Grade Level / Age Range:

Grades 3

Time:

2 hours total or two 50-minute class periods

Purpose:

Address core science standards by teaching students how wind turbines turn wind energy into electricity. Students will investigate balanced and unbalanced forces and magnets.

Materials:

Suggested Companion Resources (books and websites)

Vocabulary (with definitions)

  • Electron: a part of an atom that has a negative charge. Electrons flowing through wires create electricity.
  • Magnet: a material that produces a magnetic field
  • Magnetic field: a force that has positive attractions and negative attractions. Similar forces repel each other. For example, a negative magnetic pole will repel a negative electron. Opposite forces will attract each other. For example, a positive magnetic pole will attract a negative electron.
  • Turbine: a device that converts the wind's kinetic energy into electrical energy.

Background – Agricultural Connections (what would a teacher need to know to be able to teach this content)

Wind is caused by atmospheric pressure changes that occur because the sun heats air in some areas more than others. For more information on how wind forms, including some helpful graphics illustrating how air pressure differences start the wind blowing, see USA TODAY's Weather Basics section on Understanding Winds.

The power of wind energy can be harnessed to generate electricity. To make electricity, the shaft of a wind turbine is connected to an electrical generator at the top of the turbine's pole or tower. The generator converts the mechanical energy of the spinning turbine shaft to electricity and sends that energy down the tower along wires to a power grid or energy storage area. See the NOW Web site's close-up of a wind turbine for additional detail on how they work.

How Many Blades? Most wind turbines use either two or three blades. Research indicates that as more blades are added there is an increase in aerodynamic efficiency, but this efficiency decreases dramatically with each added blade. For example, increasing the number of blades from one to two can yield a six percent increase in aerodynamic efficiency, but increasing the blade count from two to three yields only an extra three percent in efficiency. And, of course, there are cost implications, too. Each additional blade in a design will increase the cost of the end product, so engineers have to factor in both the increased efficiency and the increased cost of manufacturing to determine a design that will be the best for an application. Aesthetics is also a consideration. A small, two or three blade design might be best for a residential area, where a homeowner just wants to pull from the wind enough energy to power their own home, and would prefer a quieter option. A giant 12 blade design would not look very nice atop their home and would perhaps generate more energy than they need, and likely more noise, too!

Interest Approach or Motivator

Flick the light switch in the classroom on and off several times to gain student’s attention. Ask them what is it that turns the lights on and makes them bright. Possible responses may include: power, light, electricity, energy. Confirm with them that it is electricity that gives the light bulbs their energy to produce light. Ask students where does that electricity come from. Possible responses might be: the wall, the outlet, the power plant. Accept all suggestions. Then focus the conversation by saying “Today we are going to learn about electricity that is produced from the wind.”

Procedures

  1. Introduce students to the book My Family’s Wind Farm. Either display the digital copy of the book on a large screen that all students can see or provide hard copies to each of the students. As a class, read the book aloud together. Assign a different student to read each page. Only read the story on the top of each page (ignoring the smaller print type in the purple boxes at the bottoms of the pages). Debrief after reading with the following discussion facilitation questions:
    1. What is the main idea of the story?
    2. Where does Callee live?
    3. What does Callee’s family do for a living?
    4. How is their farm unique or different?
    5. What is a natural resource?
    6. How does Callee use the electricity that is produced by the wind turbines?
  2. Read the book again. Assign struggling readers to read some of the same passages to practice repetition and fluency. Assign more advanced readers to read the supplementary text in the purple boxes at the bottom of each page. Facilitate discussion with the following questions. Focus on finding facts and details in the text. Have students refer to the book as needed.
    1. How tall is a wind turbine?
    2. Why is Iowa a good place to build wind turbines?
    3. How fast does wind need to blow to produce electricity in a wind turbine?
    4. How does a wind turbine produce electricity?
    5. Where does the electricity that is produced go?
    6. How do we measure electricity? How much electricity can a wind turbine produce every year?
    7. How does Callee’s family decide to plant soybeans or to build wind turbines on their land?
  3. Tell students that motion in the form of wind can turn the blades of a turbine to produce electricity from a generator. Describe a wind turbine (300 to 400 feet tall; each blade is 100 feet long; turbines are located on windy ridge tops). Explain that the wind rotates the blades and that causes the shaft in the generator to rotate near magnets and coils of wire and that creates electricity that flows through wires down the tower. The electricity from many wind turbines is collected in a central location, then sent through wires under the ground to transmission lines.
  4. Explain that magnets located inside turbine generators produce electricity by their magnetic field causing electrons from atoms in wire to flow. Ask students to write in their science notebooks this main idea: Magnets can cause electrons to jump from one atom to the next atom in a wire. A magnetic field (magnets) can “push” electrons from atoms to make them move. Some metals, like copper, have electrons that are loosely held and atoms within copper wire are easily moved from atom to atom.
  5. Tell students that “power plants use magnets” to “push” electrons in wires to make electricity. Show students a diagram of a wind turbine and point out the location of the magnets and the coils of wire. (Note that magnets can be located outside of the copper wire with the turbine spinning the wire, or the magnet spinning inside surrounded by stationary copper wire.)
    1. Wind Turbine diagram 1: http://windeis.anl.gov/guide/basics/turbine.html
    2. Wind turbine diagram 2: https://commons.wikimedia.org/wiki/File:Wind_turbine_diagram.svg
  6. The Power of Magnets: Using two bar magnets lying flat on a surface, show students how one magnet can “push” the other magnet without ever touching it. Explain that this is a visual representation of a magnetic field; you can now imagine how the magnetic field created by the magnets in a turbine generator can “push” the electrons in the coils of wire and create electricity (the flow of electrons).
  7. Activity: Build a wind generator. A teacher may elect to build one demonstration version of this to present to and display to the class. Or with more advanced students, the teacher can break them into small working groups and have each group build the wind generator. The tactic chosen will dictate the number and amount of materials needed. The teacher may want to be in charge of the drill and hot glue gun for all projects to minimize risk to students.   https://www.exploratorium.edu/snacks/light-wind
    1. A generator is a device that converts mechanical energy into electrical energy. This is the opposite of how a motor works, which uses electricity to create motion. This activity uses a hobby motor in reverse to create an electric current. By attaching blades to the motor, wind can be used to provide mechanical energy to the motor so that it works like a generator and supplies electricity. This electrical output could be measured with a multimeter, but an LED provides an easy readout that shows power is being generated. This simple wind generator is a model for wind turbines used to generate electricity around the world. Though they operate on a larger scale, they use the same physical principles to convert wind energy to electricity.
    2. Cut the sides of the small cup into four equal parts. Remove the base to create four curved pieces that will be the blades of the wind generator.
    3. Use hot glue to attach two craft sticks together at the center so they make a plus sign.
    4. Once the glue is dry, drill a small hole the size of the motor shaft in the center of the craft sticks. This will serve as the frame for your blades.
    5. Glue a blade to each of the craft stick ends. The blade design has the greatest impact on the efficiency of the wind generator; this is just one way to do it. Feel free to try materials other than a cup to construct something you think will best utilize the wind to yield the most rotations per second.
    6. The hobby motor should have two small prongs sticking out of the back that serve as the terminals where you would normally attach a power source. Instead, attach an LED to the back of your motor by twisting each leg of the LED through a different terminal on the back of the motor. The correct orientation of the LED will depend on whether the blades spin clockwise or counterclockwise, so you will know if you need to switch it once you test the windmill. Slide your blade frame onto the shaft of the motor.
    7. Glue one end of each of the other two craft sticks on either side of the larger cup to make a stand that holds the motor above the cup like chopsticks. Glue the other ends of the craft sticks directly to opposite sides of the motor to hold it in place. Make sure the motor is positioned so that the stand does not obstruct the ability of the blades to turn freely.
    8. Test out your wind generator with a fan or on a windy day. Can you generate enough power to light an LED? Note: LEDs only work in one direction in a circuit. Your motor will output DC current, but it may be in the reverse of the direction your LED needs. If you have trouble getting the LED to light up, try switching the leads to make sure it’s connected in the correct orientation.
    9. Point out to students that our small demonstration wind generators have the same parts as a large 300-foot-tall wind turbine: magnet, shaft, coils of wire
    10. Using the demonstration model or the student’s own creations pose the following questions:
      1. What would happen if we removed one or more of the blades? Would the turbine be balanced? Would it still work? Remove one of the blades and test the student hypothesis.
      2. What would happen if one blade was weighted more heavily than the others? Reattach the blade and glue a penny or paper clip to it. Test the student hypothesis.
      3. What other ideas can the students come up with to test? (one blade is longer than the others, one blade is skinnier or wider than the others, one blade has a different shape, etc.) Test these variants with whatever class time allows.
  8. Review: Continue to facilitate class discussion.
    1. Can magnets be used to generate electricity?
    2. Ask students to illustrate a wind turbine labeling as many parts as they can remember. Ask them to write a short paragraph describing how a wind turbine can turn wind into electricity.

Did you know? (Ag facts)

  • When several farmers join together to form a business it is called a cooperative or co-op. Co-ops can sell seed, animal feed, fertilizer, chemical, or a variety of other products.
  • An acre is a measure of land approximately the same size as a football field.
  • One wind turbine produces approximately 6 million kilowatt hours or kWh per year - enough to supply 1,500 average households with electricity.
  • An iPad uses about 11 kWh of electricity per year.
  • A refrigerator uses 350 kWh of electricity per year.

Extension Activities (how students can carry this beyond the classroom)

Sources/Credits

Author(s)

Will Fett

Organization Affiliation

Iowa Agriculture Literacy Foundation

Agriculture Literacy Outcomes

  • T1.3-5.e. Recognize the natural resources used in agricultural practices to produce food, feed, clothing, landscaping plants, and fuel (e.g., soil, water, air, plants, animals, and minerals)
  • T4.3-5.a. Compare simple tools to complex modern machines used in agricultural systems to improve efficiency and reduce labor
  • T4.3-5.d. Provide examples of science being applied in farming for food, clothing, and shelter products

Education Content Standards

  • Science:
    • 3-PS2-1. Plan and conduct an investigation to provide evidence of the effects of balanced and unbalanced forces on the motion of an object.
    • 3-PS2-3. Ask questions to determine cause and effect relationships of electric or magnetic interactions between two objects not in contact with each other.
    • 3-PS2-4. Define a simple design problem that can be solved by applying scientific ideas about magnets.

Common Core Connections

  • English Language Arts:
    • RI.3.2. Determine the main idea of a text; recount the key details and explain how they support the main idea.
    • RI.3.3. Employ the full range of research-based comprehension strategies, including making connections, determining importance, visualizing, making inferences, summarizing, and monitoring for comprehension. RI.3.5. Use text features and search tools (e.g., key words, sidebars, hyperlinks) to locate information relevant to a given topic efficiently.
    • RI.3.7. Use information gained from illustrations (e.g., maps, photographs) and the words in a text to demonstrate understanding of the text (e.g., where, when, why, and how key events occur).
    • RI.3.10. By the end of the year, read and comprehend informational text, including history/social studies, science, and technical texts at the high end of the grades 2-3 text complexi9ty band independently and proficiently. (RI 3.10)

 

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