Teachers TryScience

Investigation 1: Where does my electricity come from?

Teacher Preparation

Prior to Investigation 1, be sure to research the sources your state or city utilizes for energy production. You can use the U.S. Energy Information Administration or other government websites to find this information. This will help you guide students as they research energy production during the investigation.

Materials

• Energy readings
• Computers or tablets for Internet research

Instructional Sequence

Begin by asking students to do a quick write on the following prompt: “Where does your electricity come from?” Use this paragraph as a tool to assess student thinking and prior knowledge.

For students who might struggle with writing, you can ask the class to create an annotated drawing instead of a full paragraph.

Next, ask students to think about everything they did from the time they woke up in the morning to the time they made it to class. Ask them to work with a partner and create a list of all of the items they used that needed electricity during that time period. Responses might include turning on a light, running an appliance for breakfast, using a hair dryer, using a crosswalk signal to cross a street safely, etc.

For students who may not have access to electricity at home, you can focus their attention on electricity use in the classroom only.

Then, return to the quick write and ask students to share some responses about where they thought their electricity came from. Capture their responses on the board. Some students might focus on a location of where the electricity is produced while others might share thoughts on the process used to generate electricity. By capturing the responses on the board, you can create a fuller picture of the classes’ thinking on this topic.

Split students into small groups, and ask them to research where the electricity to power the school comes from. Provide students with high interest less direction about what sources to use for their research. Provide struggling students with a list of websites you’ve identified during your lesson preparation. You can also group together students with varying levels of ability so they are able to work with and learn from each other.

After groups have had time to research, ask each group to share some of what they learned about the sources of the school’s electricity. Highlight the fact that electricity rarely comes from a single source, but rather is generated by a variety of sources.

Be sure to differentiate between electricity and energy in general. Students should understand that electricity is a type of energy. Not all energy sources are used to produce electricity.

Instruct students to return to their groups and provide each group readings about a different source of electricity. As they are reading, students should take notes on the tradeoffs associated with their source.

If needed, you can use a class discussion to identify some potential tradeoffs prior to passing out the readings. Tradeoffs could include cost/economic factors, level of adoption, maintenance efforts, or impact on the environment or society. For students who need extra support, create a worksheet to guide their reading.

Sample Readings

http://energy.gov/articles/potential-path-emissions-free-fossil-energy

http://energy.gov/articles/turbines-nyc-east-river-will-provide-power-9500-residents

http://energy.gov/articles/americas-wind-industry-reaches-record-highs

After students have had time to read and take notes, ask each group to share their findings. Use student responses to highlight the idea that meeting society’s energy demands in a sustainable manner is a challenge and that there are tradeoffs associated with every type of energy source. Have students discuss how engineers/scientists are trying to apply their scientific knowledge to create sustainable energy sources that increase benefits but that try to decrease the costs and risks. Have students identify and discuss the benefits, costs, and risks associated with each energy source.

Ask students to use their science notebooks to jot down some ideas about possible solutions to this challenge. Remind students to use what they’ve learned from their research and their readings to support their answers.

Investigation 2: Designing a Wind Turbine

Teacher Preparation

Prior to class, create your own model turbine that can be used for a demonstration. See the Instructions for Turbine Set Up document.

Materials

The class will need

• Voltmeter
• Fan or hair dryer
• Demonstration turbine system

Each group will need an assortment of the following:

• Wide mouth straws
• Clay
• Skewers of different sizes
• Toy motor/generator
• Rubber band or electric tape
• Wires
• Voltmeter
• Index cards of different shapes or sizes
• Scotch tape
• Scissors
• Masking tape
• Pencil
• Two rulers

Inform students that they will now be focusing on providing energy for their local community. Their community is considering the adoption of an alternate energy source that meets their energy demands but that also minimizes pollution in their area. The community is interested in investing in wind energy specifically and wants to make sure they make a well informed decision about whether wind energy is a good option for their community. Tell students they will write a memorandum to the community panel about whether wind energy is a reliable source for the growing needs of their community and what the costs, risks, and benefits associated with it will be. In order for the community panel to make an informed decision, they will also need to know the details about how wind turbines work and whether they will be effective and efficient in their community’s environment.

Be sure to provide students information about the geography of the area as well as the economic and social profile of the community members. You can provide the information through readings, visuals, or orally, but be sure to provide accommodations for different types of learners.

Ask students what they need to learn about and investigate before they can write their memorandum and recommend or not recommend the use of wind energy by their community. Encourage them to ask questions that they would like answered before they write the memorandum. Write the ideas and questions up on the board. The ideas should be inclusive of the following: how wind energy can be used to generate electricity; how much it will cost to use wind energy; what the benefits are; what the impacts are on the environment, society, etc.; how much space is required. If students do not come up with the idea that they need to know how wind energy can be used to generate electricity and that they need to know the different types of turbine models to know which one is the most efficient and effective for their community, then prompt them toward those ideas.

Tell students that a wind turbine system uses wind energy to generate electricity. Ask students to jot down three things that they think are necessary for a wind turbine to generate electricity. This can be used to assess students’ familiarity with the concept.

Present students with images of wind turbine systems. Ask students to work with a partner to write down any commonalities they notice across turbines. These images can also be used to supplement students’ prior knowledge and provide a common foundation for the rest of the lesson. For students who might be struggling or who might not be familiar with wind turbines, you can provide a pinwheel or other simple mechanism as a foundation.

Ask students, “How do you think the movement of the turbine blades results in the production of electricity?” Use student responses to highlight the idea that the kinetic energy of the wind is transferred into mechanical energy and the mechanical energy from the movement of the turbine blades spins a shaft, which turns a generator that converts the mechanical energy to electrical energy.

For more information: http://energy.gov/eere/wind/how-do-wind-turbines-work

For students who might be struggling, spend time creating working definitions of terms such as “generator”.

You can also use videos or animations to help support students’ understanding of how a turbine works.

Sample Video

http://energy.gov/eere/videos/energy-101-wind-turbines-2014-update

Next, ask students to work individually to use the information from the videos and the conversation to create a diagram indicating where energy is flowing in the wind turbine system. Students should identify the input of energy into the system, the flow of energy through the system (including any energy transformations that occur) and the output of energy from the system. You can use this as a formative assessment tool to gauge student understanding of energy flow in turbine systems.

Ask students to share their responses with the class. It is possible that students did not draw and/or identify every part of the energy flow through the system, and this class discussion will help them see if they are missing any parts. Likewise, students may identify parts of the turbine system they included that do not relate to the flow of energy and therefore do not need to be part of their diagram. You can also use this time to review any energy concepts, if necessary. After the class discussion, tell students to return to their groups to create a final diagram on chart paper of how energy flows through the system as well as the inputs and outputs of the system. They should work on combining their individual diagrams as well as any modifications they noted during the class discussion. Make sure students identify the different forms of energy throughout the system. Input as kinetic energy in the form of wind à the kinetic energy is converted to mechanical energy à the generator converts the mechanical energy to electrical energy. Post the diagrams in the room.

Transition to the next part of the investigation by informing students that although most wind turbines rely on the same transfer of energy they outlined in their diagrams, some turbines work better than others because of their structure/size, how they were built, their components, etc.. Environmental factors, such as wind speed or wind angle, can also affect how well wind turbines work in a particular environment. Inform students that for them to be able to make recommendations about whether wind energy is a suitable alternative for their particular community, they need to understand the design of wind turbines and the effectiveness of the designs. In order to understand those aspects, tell students they will be designing and building their own turbine systems and then testing them. Ask students “How can we measure the effectiveness of a wind turbine system?”

Next, use the fan to demonstrate to students the model turbine system you have created. Have one student come up and read the output of the voltmeter. Tell students that the voltmeter measures the amount of voltage passing between two points in the electrical system, which is an indicator of how much electricity is being generated. Help students come to the understanding that the higher the voltage reading, the more electricity the turbine is generating, and therefore, the more effective it is.

Present students with the materials that they will have to build their turbine and tell them that they will have one and a half class periods to create their turbines.

Now that students have seen the materials they are using, again ask students “How can we measure the effectiveness of a wind turbine system?” Working as a class, more clearly outline the criteria and constraints (both qualitative and quantitative) of the design process. For example, the class might articulate, “Using only the materials and time allotted, we will create wind turbine systems that produce at least 2.5 volts of electricity.” Write the list of criteria and constraints up on the board so students are aware of what they need to consider when designing their systems.

The motors that students will be using will have voltage limits. Help guide students in creating criteria within these limits.

Split students into small groups. Instruct each group to examine the available materials, consider the criteria and constraints, and then create a drawing of their design. As you walk around, prompt students to describe how the structure or function of the materials they’ve chosen might affect the functioning of their turbine.

After you have approved their design, tell students to draw out the energy flow in their turbine system. They should include the input of energy, the transfer and flow of energy through the turbine and the output of energy. Once the group finishes illustrating the energy flow, have them explain to you what is going on in the energy flow and how their turbine’s design is allowing for the energy flow to occur. You can also prompt them to think about how the energy flow in their system is the same or different from the previous energy flow diagram they created earlier in the lesson. Then, you can allow students to begin building their turbines.

For students who need extra support, you can make the design process more guided. You can also provide students with your demonstration turbine system for reference.

After all groups have finished building, inform the class that it is time to test the turbines.

Ask students to think about and discuss how they can test their turbine systems and what they want to get out of the testing (what data do they want to record from the testing). Students should be discussing how they want to measure how effective their turbine system is and how this can be indicated by reading the voltage output. Tell students to work individually and use their experiences designing the turbine to create a list of potential features of their turbines they think might be noteworthy and that could be included in a data collection table. Students should also articulate how much data they think they need to collect and the type of data they need to collect to ensure reliable measurements. They should think about different environmental factors they can expose their turbines to, in order to see if the effectiveness of the turbine is affected. Encourage students to not only think about the turbine itself, but also the turbine’s interaction with the wind. Responses might include number of blades, shape of blades, size of blades, angle of the fan, or temperature of the wind. You can use this list as an assessment tool.

Have students share out their responses to create a data collection table that can be used to record information during testing. All groups should record observations and results for each group.

Ask students how they can ensure that the testing is fair and even across groups. Record their responses to generate a testing protocol for all of the designs. Responses might include keeping the fan at the same distance and speed for each test, a non-group member reads the voltmeter for each test, etc.

Sample Data Collection Table

Group #:

Using the student-generated testing protocol, have each group test their design.

After all groups have tested, ask students to share what they thought worked well across designs. Encourage them to use their notes and the data to justify their responses. You can use the following questions to guide your discussion. Also, encourage students to ask questions to each other about their designs and the collected data. Was there any design that seemed to work better than others? If so, how were its components different than the other designs? How do you think that impacted its transformation of energy and effectiveness? Did any turbine systems work better for certain environmental factors? If so, how do you think system’s design/components influenced the system’s performance when exposed to those environmental factors?

As a whole class, engage in a class discussion about the designs and the testing protocol. Use the following questions to guide the discussion.

• What were some limitations of your designs?
• How accurate was your data collection process? Justify your response.
• What were some of the limitations on the precision of your data?
• Did the data you collected help answer the question “How can we measure the effectiveness of a wind turbine system?”
• Did you collect a sufficient amount of data to make claims about how various features of your design affect the functioning and effectiveness of the turbine?
• How could your designs potentially be modified? Why would you implement those modifications? What energy processes would they affect and how?

Tell students that they will be improving upon their designs. Remind students that iteration and improvement is a key piece of the design process.

Now, using the same process, students should refine their designs, and then retest. When refining their designs, students should illustrate the changes on their original design sketch and describe how the modifications will make their systems more effective.

For students with high interest, you can change the criteria so that groups are required to increase the voltage produced by their design. You could also use an extension in which students redesign their turbines for use in water (hydropower).

Investigation 3: Wind Turbines in the Real World

Materials

• Energy readings
• Computers or tablets for Internet research

Instructional Sequence

Transition by again asking students what features seemed to work well across designs. Continue by asking them to make claims about how environmental factors such as wind temperature or angle of wind affected the performance of the turbines. Based on this information, ask students to name some areas of the country (or the world) where they think it might make sense to use wind as an energy source. Encourage them to use their notes to justify their responses.

Next, provide students with information about real wind turbine projects. The information should include data about space needed for turbines, geographical or topographical requirements, costs, and environmental impact.

Sample Readings and Media

Green Light Wind Farm Slide Show

http://www.epa.gov/cleanenergy/energy-and-you/affect/non-hydro.html#wind

http://www.awea.org/About/landing.aspx?ItemNumber=5237&navItemNumber=633

http://energy.gov/eere/renewables/wind

http://energy.gov/eere/wind/environmental-impacts-and-siting-wind-projects

You can use a jigsaw strategy and assign small groups a different reading that they will then present to the class.

After students have had time to read and research information about what is needed to effectively utilize wind as an energy source, work as a class to consider under what circumstances a wind turbine might be best for their local community. What are the costs and benefits associated with wind energy? Are there environmental issues that need to be taken into account? Impacts to the community, either positive or negative? Are there any technologies or regulations that can mitigate the costs and/or negative impacts?

Remind students that there is no one ideal energy source. As they saw in investigation 1, electricity for a school or community can come from a combination of sources. As they saw in investigation 2 and 3, different energy sources work best in different environments or scenarios. Tell students that they will now be writing a memorandum to the community panel articulating whether or not the community should invest in wind turbines. The memorandum will be in the form of an argument and should begin with a claim about whether they recommend or do not recommend the use of wind energy for their community. It should include evidence to support the claim, and the evidence should come from their research, their design process, and the data they obtained from their investigation. The evidence and reasoning should take into account any impacts the wind turbine can have on the community including any associated economic, social, environmental, and geopolitical costs, risks, and benefits. Any alternative interpretations of the evidence should also be included, along with why the chosen evidence supports the claim as opposed to any other claims. The memorandum should include information about whether wind energy is or is not a reliable source of energy for the community (keeping in mind the characteristics of the community and the environmental factors), including a discussion about the processes of energy transformation that occur and the output of electricity. They should use their research and results from all of the investigations to support their answer. You can also allow time for additional research or questioning about the pertinent geographical, social, economic and environmental characteristics of the community.

Depending on how comfortable your students are in constructing arguments, you may wish to provide more or less support in the directions.

Review the Wind Writing Rubric as a class and provide students time to ask clarifying questions. You can also use elements from the Original Wind Rubric in your assessment.

For students with high interest, you can ask them to research additional renewable energy sources and ask them to apply this research to describe the ideal energy portfolio for the target community.

For students who are struggling, scaffold the research process and provide opportunities for check-ins so you can give targeted feedback.