# LessonExploring Energy: What Is Energy?

### Quick Look

Time Required: 1 hour

Lesson Dependency: None

Subject Areas: Physical Science, Physics, Science and Technology

NGSS Performance Expectations:

### Summary

Students are introduced to the definition of energy and the concepts of kinetic energy, potential energy, and energy transfer. This lesson is a broad overview of concepts that are taught in more detail in subsequent lessons and activities in this curricular unit. A PowerPoint® presentation and pre/post quizzes are provided.
This engineering curriculum aligns to Next Generation Science Standards (NGSS).

### Engineering Connection

We are surrounded by and interact with energy every day and thus energy is an important concept across all fields of engineering, including civil, mechanical, electrical and aerospace. Applying an understanding of energy enables the design of products, tools and technologies that require energy use, storage and transformation.

### Learning Objectives

After this lesson, students should be able to:

• Define energy, kinetic energy and potential energy.
• Identify the existence of energy with examples from daily life.
• Explain the concept of energy conversion.

### Educational Standards Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards. All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org). In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

###### NGSS: Next Generation Science Standards - Science
NGSS Performance Expectation

MS-PS3-5. Construct, use, and present arguments to support the claim that when the kinetic energy of an object changes, energy is transferred to or from the object. (Grades 6 - 8)

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This lesson focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices Disciplinary Core Ideas Crosscutting Concepts
Science knowledge is based upon logical and conceptual connections between evidence and explanations.

Alignment agreement:

When the motion energy of an object changes, there is inevitably some other change in energy at the same time.

Alignment agreement:

Energy may take different forms (e.g. energy in fields, thermal energy, energy of motion).

Alignment agreement:

###### International Technology and Engineering Educators Association - Technology
• Energy is the capacity to do work. (Grades 6 - 8) More Details

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###### California - Science
• Construct, use, and present arguments to support the claim that when the kinetic energy of an object changes, energy is transferred to or from the object. (Grades 6 - 8) More Details

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### Introduction/Motivation

Today is the first day of our unit on energy. Energy is evident all around us every day and is a fundamental concept that is used by engineers who design the many products and technologies in our world—such as cars, phones, electronics, appliances, roller coasters, rockets, and more. Let's begin by watching a video. (Show students the four-minute video, MythBusters-Exploding Water Heater, at https://www.youtube.com/watch?v=jbreKn4PoAc.)

What did you notice? (Have students share their responses.) What questions do you have? (Have students write them down in their notebook.)

What we just saw is an example of a lot of energy being released in a short amount of time. When we get to the end of our lesson on energy, you'll be able to understand what we saw in the video and explain it to your friends.

(Continue by showing the presentation and delivering the content in the Lesson Background section.)

### Lesson Background and Concepts for Teachers

Students entering sixth-grade generally have a limited understanding of what energy "is," and sources of energy. This lesson aims to assist students in identifying types of energy, and how energy is used and transferred. Gaining this understanding lays the foundation for further learning during the subsequent lessons of this unit, and gives students the pre-requisite knowledge they need to study more complex concepts related to energy.

Inform students that this lesson is a "keystone" lesson that covers very basic, yet important concepts that will be built upon in subsequent energy-related lessons. Without a basic understanding of what energy is, students may have difficulty grasping more detailed or complicated ideas presented in future lessons.

Teach the lesson using the 13-slide What Is Energy? Presentation, a PowerPoint® file, along with the notes provided below. The presentation is animated, so clicking brings up the next image, text or slide. The presentation contains review questions and activities that ask students to use their new energy knowledge. The associated activity, Spool Racer Design & Competition,  also provides opportunities to discuss and review key concepts.

What Is Energy?

(Slide 1) Begin with any engaging demonstration or video related to energy. As one suitable example, the slide provides a link to an exploding water heater clip from MythBusters. Start with the Introduction/Motivation content, explaining that this is the first day of a unit on energy—a fundamental science concept that engineers use to design the products, tools and technologies we depend upon every day, and that by the end of the lesson, students will be able to understand and explain what happened in the demonstration. Then ask the class for answers to the question "what is energy?"

At this point, we do not recommend explaining the details of the video. Students have not yet learned the energy concepts displayed in the video demonstration. By the end of this lesson, expect students to be able to explain that the MythBusters put energy into the water heater by connecting it to the electrical outlet. When the temperature and pressure in the water heater increase, they build up the potential energy. When the water heater explodes, the potential energy is converted to kinetic energy. By the end of this unit, expect students to be able to explain more details of the video, such as the forms of energy present.

For the teacher, the following is a detailed explanation of what happens in the video: The MythBusters put electricity into the water heater. That electricity is transferred to thermal energy by the heating element. Thermal energy builds up in the water heater (potential energy), causing an increase in the temperature of the water and an increase in the pressure inside the water heater. The MythBusters disabled the safety valve that prevents a normal water heater from building up too much pressure. The boiling temperature of water increases as pressure goes up. At atmospheric pressure (14.7 psi), water boils at 100 °C, but at 332 psi, the maximum pressure shown in the video, water remains liquid up to 219 °C. When the water heater bursts and the pressure drops suddenly from 332 psi to 14.7 psi, the water is 119 °C above its boiling point. The superheated water boils suddenly and violently as much of the water is converted to steam. The steam expands out from the water heater (kinetic energy), sending the water heater and pieces of the surrounding shack flying (also kinetic energy). It also creates a loud noise; sound is another form of energy.

(Slide 2) Using the examples shown ask students which of the five pictured items have energy and why they think so.

• Apples: Food must have energy, since we get energy from eating it.
• Violin players: Both the sound of the violins and the motion of the violin players are evidence of energy.
• Fire: The light, heat and sound of a campfire are all evidence of energy.
• Car: In this case, either answer might be correct, depending on how students justify their answers. This car is motionless, so no sign of energy exists in the picture. However, students might correctly note that cars usually have fuel and/or batteries, both of which contain energy.
• Rock: This rock has energy stored due to its height. Even though no motion, heat, light or sound is happening now, it has stored energy that would be released if it tipped over.

Ask students if they can come up with a definition for energy based off of the examples above and what clues exist that indicate the presence of energy. (Have students discuss; get students to say that energy is the ability to make things happen. Motion, heat, light and sound are clues that energy is present.)

(Slide 3) Show students the image of a bow being pulled back. Ask students, does this have energy? Where is the energy?

(Slide 4) Now show the images of the compressed springs, chemical batteries and expanded elastic balloons. Ask students, what do these all have in common in terms of energy? What type of energy is this? Allow students to share their thoughts. Guide them to understand that all of these objects have potential energy- which is energy that is stored. Ask students to come up with other examples of potential energy.

(Slide 5) Now show the image of an arrow that has been released. Ask students, what type of energy does the moving arrow have? How is this energy different than when the bow was pulled back?

(Slide 6) Now show the images of kids running on a field as they play soccer and a race car traveling around a track. Ask students, what do they have in common in terms of energy? What type of energy is this? Allow students to share their thoughts. Guide them to understand that all of these are examples of kinetic energy- which is energy of motion. Ask students to come up with other examples of kinetic energy.

(Slide 7) Now ask students how the potential energy from the pulled bow resulted in kinetic energy of the moving arrow? Allow students to share their thoughts. Guide them to understand that the bow and arrow is a classic example of energy transfer. That is, energy can be transferred from one type to another, as with the pulled bow (potential energy) transferred to a moving arrow (kinetic energy).

(Slides 8-12) Numerous examples are provided to help students think intuitively about relative amounts of energy and energy conversion. Objects that look the same represent the same mass. For example, the springs on slide 10 are identical. It is recommended to not identify the particular types of potential energy present in these examples because the types of potential energy are not introduced until the next lesson. However, if desired, explain that energy stored in an object's height is called gravitational potential energy and energy stored in a compressed spring is called elastic potential energy.

(Slide 13) Administer the post-quiz, as described in the Assessment section. Then make a short writing homework assignment, as described on slide 13 (and in the Assessment section).

### Associated Activities

• Spool Racer Design & Competition - Students brainstorm, design, experiment with, and race spool racers as they redesign to meet various design criteria. These devices store potential energy in twisted rubber bands and then convert the (stored) potential energy to kinetic energy (motion).

### Vocabulary/Definitions

conservation of energy: A fundamental law in thermodynamics. It states that energy cannot be created or destroyed; it can only change from one form to another.

electricity: The flow of electric charge through a conductor. Energy can be transferred from one place to another and from one form to another by electricity.

energy: The ability to make things happen. More advanced definition: The ability to do work.

force: Energy can be transferred from one object to another by a force (by the objects pushing or pulling on each other). A force can also transfer energy from one form to another.

gravitational energy: Energy that is stored in the height of objects. Gravity is the force that pulls things down to Earth. The higher an object, the more gravitational energy it has. Often, gravitational energy (a form of potential energy) is converted to kinetic energy to make things move fast.

kinetic energy: The energy of moving objects. Anything in motion has kinetic energy. The faster an object moves, the more kinetic energy it has.

potential energy: Energy that is stored and can be used when needed. Energy can be stored in chemicals (food, batteries), height (gravitational), elastic stretching, etc.

### Assessment

Pre-Lesson Assessment

Pre-Quiz: Prior to starting the lesson, administer the three-question What Is Energy? Pre-Quiz to assess students' prior knowledge of energy, kinetic energy and potential energy.

Post-Introduction Assessment

Discussion Questions: Use class discussions and student writing assignments to evaluate student knowledge. Throughout the What Is Energy? Presentation are many opportunities for quick assessments of understanding. For example, at slide 8 say, "I want everyone in the class to give me a thumbs-up if you think the ball on the right has more energy, and a thumbs-down if you think the ball on the left has more energy."

Lesson Summary Assessment

Post-Quiz: Administer the five-question What Is Energy? Post-Quiz to assess students' understanding of the concepts presented in the lesson, including energy, kinetic and potential energy and energy conversion. Review their answers to gauge their level of comprehension.

Homework

Writing: In addition to the post-quiz, assign students to write short descriptions of what happened in the exploding water heater video using the concepts they learned in the lesson. Assign as either a small group or individual activity. Review students' writing to gauge their depth of comprehension. (Note: Students should be able to explain that the Mythbusters put energy into the water heater by connecting it to the electrical outlet. When the temperature and pressure in the water heater increase, they build up its potential energy. When the water heater explodes, the potential energy is converted to kinetic energy. By the end of the unit, students should be able to explain more details of the video, such as the forms of energy present.)

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### Contributors

Eric Anderson, Jeff Kessler, Irene Zhao

### Supporting Program

RESOURCE GK-12 Program, College of Engineering, University of California Davis

### Acknowledgements

The contents of this digital library curriculum were developed by the Renewable Energy Systems Opportunity for Unified Research Collaboration and Education (RESOURCE) project in the College of Engineering under National Science Foundation GK-12 grant no. DGE 0948021. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.