The lesson presented here focuses on the engineering design process and its use in identifying a question (solving a problem), developing a design or change in design, testing that design, observing and collecting data, analyzing the data recorded from the experiment, and forming a conclusion to perform another round of design. In this case, we are attempting to maximize the voltage obtained from a wind-driven turbine through the use of several experimental designs.
You may want to review the following multimedia presentations to learn more about STEM and the engineering design process.
Instructions for creating a wind-powered electrical generator
The teacher should be sure to create a wind generator and test out the procedure prior to the implemenation of the lesson. The following instructions, which include the video below, are a suggested baseline approach to teachers in preparing the lesson and building their personal turbine/generator/voltmeter apparatus.
- Creating a Wind-powered Electrical Generator
Cut a two-centimeter length of a wide mouth straw and insert a skewer into the side of the straw length such that the end of the skewer comes out of the other side. Make sure that an even length of skewer is sticking out of both sides of the straw. Repeat this procedure with one more skewer, inserting the skewer perpendicular to the first skewer. The two-centimeter length of straw should now form an axis, it’s center being “crossed” by the skewers. In all, this should form a turbine without blades attached to the skewers.
Using the pencil and ruler, draw a blade on the index cards. As the blades are drawn, keep in mind that the goal of the activity is to maximize the voltage that will be read on the voltmeter. To achieve this, the shaft of the motor/generator must spin fast. Hypothetically, the more the blades can “catch the wind”, the faster the turbine will spin thus generating a larger current and, therefore, voltage. Once the blades have been designed, tape them to the skewers forming the wheel of the turbine. Remember, to get the turbine to spin quickly, they should tape the blades to the turbine in such a way that wind from the hairdryer will hit the blades with a great deal of force or such that the surface area and the angle of the blades will be maximized.
Instructions for Setting Up the Generator and Voltmeter and Adhering the Propeller (Turbine) to the Generator
Using masking tape, tape a ruler to a desk making sure that at least 5 cm of the ruler is extended off of the table. With the rubber band or electrical tape, attach the toy motor/generator to the part of the ruler that is extended off of the table making sure the shaft of the motor/generator is suspended off the edge of the ruler. This will give some distance between the turbine and the table such that the blades of the turbine do not hit the table. As a practice test, the instructor should attach the turbine that they he or she creates to the shaft of the generator to ensure that the distance between the blades and the table are sufficient to prevent any interference of the blade movement by the table. Wires should be connected from the generator to the voltmeter such that a voltage is registered when the generator’s shaft is rotated. The clay should be placed into the wide mouth straw (central axis of the turbine) to allow the turbine to “stick” to the shaft. By blowing a hairdryer across the turbine, it should rotate, consequently registering a voltage on the meter.
Introductory Discussion Talking Points
The teacher should approach the introduction of the lesson the way they deem most beneficial to their students. However, the key is to allow the students to become active participants in their own learning using prior knowledge, experience and self-inquiry.
Engage the students in a discussion in which they express what they know about wind, electricity and how wind can be harnessed to power an electrical generator. The following video may inform your teaching:
A discussion of how fossil fuels generate electricity should take place. Emphasis on the