Academic journal article Science Scope

Windmills Are Going around Again

Academic journal article Science Scope

Windmills Are Going around Again

Article excerpt

Do all things old really become new again? Depending on your age, your mental image of a windmill may be of the classic Dutch style, the ubiquitous American farm style of the 19th and early 20th centuries, or the giant-sized wind turbines often seen today grouped in massive farms. While the design has changed over the centuries, the basic idea has remained--some type of blade captures the energy of the wind in order to turn a shaft that does some kind of work, such as turning a millstone or turning a coil of wire in a magnetic field to generate electricity. Wind is reemerging as a clean and reliable source of energy--primarily for the production of electricity.

In this 5E learning-cycle lesson, students will construct a simple pinwheel-type windmill to test the power generated by different designs. Students will compare three- and four-bladed pinwheels made from manila folders or plastic report covers. This lesson addresses the International Technology and Engineering Educators Association standard "energy is the ability to do work using many processes" (ITEA 2002, p 162). In addition, the National Science Education Standards for the middle level include the standard "energy is transferred in many ways" (NRC 1996, p 155). Energy from the Sun is transferred to wind energy, which becomes mechanical energy as the windmill turns, and then lilts a weight storing gravitational potential energy. Students will also observe a pinwheel connected to a small electric motor (cost: approximately $5), which generates electricity that will be used in turn to power a smaller motor (cost: approximately $2; motors are available through most science supply distributors) to turn another pinwheel. Here, the mechanical energy of the windmill is converted to electrical by the first motor acting as a generator, and then back to mechanical by the second motor, which finally turns another pinwheel producing wind again.

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History

People have used the energy of the wind for sailing purposes since as early as 5000 BC. Windmills were first used in China and the Middle East for pumping water and grinding grain around 200 BC. These ideas were later brought to Europe, where the Dutch improved on the design. The technology made its way to America and in the late 19th century was popular on farms and in rural areas, primarily to pump water and generate electricity. By the 1930s, most rural areas had been wired for electricity, and the use of windmills declined until the price of fossil fuels began to increase in the 1970s. Today, "wind energy is the world's fastest-growing energy source and will power industry, business and homes with clean, renewable energy for many years to come" (U.S. DOE 2005, p. 1).

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Teacher background information: Investigating windmills

Engage

Review with students safety guidelines on the use of sharp objects such as scissors and pushpins. Students should use caution when working with glue guns and wear safety goggles at all times during the investigation. Use low-temperature hot-glue guns for this activity.

To engage students you may want to show them a variety of windmill photos, easily found online by searching Google images for "windmills." Initiate a discussion of students' ideas regarding the function and purpose of windmills. Depending on your location, students may or may not have significant experience with windmills. You may also wish to have students construct a K-W-L chart with their ideas and questions about windmills.

Have students construct a pinwheel of their design. They should try to determine how moving air causes the blades to turn. This will provide some initial scaffolding experience in constructing a pinwheel before trying to make one in the Explore phase that is capable of lifting a weight.

Focus students' attention on the fact that windmills are of different design and have varying numbers of blades. …

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