What is Energy?

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Objective

Students will be able to (1) apply the 1st and 2nd Laws of Thermodynamics to potential and kinetic energy conversions and (2) describe the implications of energy conversions in determining the energy needs of organisms, ecosystems, and societies.

Big Idea

Energy is the ability to do work. It can not be created or destroyed, just converted from one form to another. Systems, both human made and natural, require energy input and conversions to function.

Introduction

This lesson covers the basic question of why systems (both organisms, ecosystems, and machines) require energy, the different forms of energy, the concepts of work and power, and the 1st and 2nd laws of thermodynamics.

 

The lesson essentially consists of two parts:

1. A pre-class textbook reading and homework assignment focused on close reading techniques, critical-thinking questions, and content vocabulary development.

2. An in class presentation that provides supplementary examples to review the concepts and vocabulary from the chapter along with a class discussion seeking to draw students into more critical examination of the topic at hand and assist in their ability to connect the concepts to their personal experiences. 

The textbook reading comes from Environmental Science: Your World, Your Turn by Jay Withgott.

If you do not have that particular textbook, I would recommend finding a similar chapter or chapters and modifying the lesson accordingly.  The concepts covered in this chapter that I would look for in a different text are...

  • a definition of energy
  • an explanation of work
  • an explanation of power
  • an explanation of the 1st and 2nd Laws of Thermodynamics
  • potential vs. kinetic energy
  • descriptions of the following forms of energy:
    • chemical
    • mechanical
    • radiant (electromagnetic)
    • thermal
    • electrical

Alternately, the powerpoint attached to the Direct Instruction section covers most of the same concepts and vocabulary as the chapter.  If you have a shorter class period, you may want to skip the reading assignment and assign the discussion questions as homework.  You could then hold the class discussion on the following day.       

In my case, I assign the textbook reading on the meeting previous to this lesson.  In that way, students will have already covered the concepts on their own and the powerpoint presentation will be less of a lecture and more of an opportunity for students to ask questions and clarify their understanding. 

 

Connection to Standard:

In this lesson, students will prepare for class by reading and determining the central idea of a text, establish familiarity with relevant scientific vocabulary, and then draw evidence from the text to support arguments and opinions presented as part of their participation in a group discussion.  

 

 

Direct Instruction

50 minutes

Like I mentioned above, I assign the textbook reading as a homework assignment to be completed upon arrival to this class period.  The powerpoint presentation is then more of a review and an opportunity for students to ask questions.  

Wondering why I choose lecture as a pedagogical strategy?  Read this rationale.

When class begins, I ask students to get their homework out and first give them about 10 minutes to discuss the critical thinking questions with their group members.  During this time, I walk around and put a stamp on completed homework and answer any questions that students bring up.  If students bring up a good question or insightful comment, I ask them to please remember to bring that up in the larger class discussion to follow the presentation.  

Affording this time before the presentation allows students to "field test" their answers with a smaller group, increasing their confidence to participate in the larger discussion.  Also, because the group shares the same grade for participation in the discussion, it allows the ideas of individual members to influence the thinking of their peers which may lead to greater insights or even new questions.  Finally, while I walk around, I listen to the nature of student discussions and get a better sense of what kinds of questions may be floating around the room, allowing me to emphasize certain aspects of the lesson or offer more detailed examples to scaffold the instruction.

After I have stamped all the homework assignments, I distribute the note sheet that accompanies the presentation.  As I've mentioned in previous lessons, offering students a note sheet provides a readymade study guide for later and allows students to focus on their thoughts and the concepts being discussed as opposed to focusing all of their attention on copying down copious amounts of notes.  

Independent Practice: What kinds of energy conversions occur when you make a phone call?

25 minutes

For this short activity, I ask students to just work with their table groups.  If there are any groups with less than 3 students, I move students around so that each group has at least 3 members.

(The instructions for this activity can also be found on the 2nd page of the notesheet.  I print the whole file out double-sided and copy it this way to save paper.)

When it comes time to grade the work, I just collect it at the end of class and quickly check off that students completed the activity before returning their work since it is on the back of their notesheet which I want them to keep. 

 

The activity is an opportunity for students to think in more detail about the kinds of energy conversions that must occur to make a telephone call.  One student is the videographer and two other students are the callers.  The videographer starts recording and says "begin" and one student picks up their phone and calls the other student.  When the phone rings and the other student answers, they say, "hello" and both students hang up.  The videographer then stops recording. 

After the recording has been made, the group watches the recording and writes down everything that happened in the table on the instructions sheet.  They then look at each activity and write down the conversions of energy that took place.  For example, if the action was "the phone's screen lit up", students may write "chemical energy > electrical energy > radiant energy" to represent the chemical energy in the battery being converted into electrical energy traveling through circuits to the LEDs of the screen that then radiate electromagnetic, or radiant energy. 

 

After students have had about 20 minutes to complete the activity and the follow up questions on their sheet, we debrief the activity in a short discussion.  

Wrap Up: Energy Conversions Discussion

15 minutes

Following the short activity on energy transfers, we have a short discussion to both debrief that activity and go over the questions from the homework assignment.

 

By this point in the year, students have gotten used to the flow of discussions and I don't really give a participation grade.  Instead, as I walk around during the beginning of the class, I talk with each group and take note of groups that have interesting answers (either that they represent the correct answer, or their "wrong" answer may illustrate a misconception that can be dispelled).  Then, if there is a lull in the discussion, I can call on those groups and ask them to share their idea I had briefly discussed with them at the top of the class.  If you are set on giving a participation grade, you can use this rubric that I used earlier in the year to determine participation grades.

 

The questions on the homework assignment were not as extensive as for some lessons earlier in the year, but it's nice to revisit the questions after the lesson as a way to make sure the students have grasped the content introduced in the lesson. 

Here's a brief guide to this short discussion

  • Compare and Contrast potential energy and kinetic energy and give an example of each
    • With this question, I'm hoping students can contrast that potential energy is due to the structure of an object (e.g., a compressed spring has more potential energy than an extended spring) or the position of an object within a field (gravitational, magnetic, etc.) whereas kinetic energy is the energy of an object in motion.  Once this basic clarification is covered, I make a quick table listing potential on one side and kinetic on the other.  I then ask students to offer some examples and I write them under the appropriate heading (e.g., potential energy could include "a book on the edge of a table", "a bowstring pulled back", or "a battery"; kinetic energy could include "a book falling", "an arrow launched from a bow", "a speaker producing sound waves", etc.)  
  • Compare and Contrast renewable energy and nonrenewable energy and give an example of each
    • This question really relates more to the next lesson on energy resources, but since there's no pre-lesson homework for that lesson, it's good to use this time to preview that lesson and compare renewable resources, which can be replenished, and nonrenewable resources which exist in a limited supply and, once they are used up, are effectively gone forever.  Since we will be spending so much time with this question in the next lesson, I'll just solicit examples from students on renewable energy resources (solar, wind, etc.) and nonrenewable resources (coal, petroleum, etc.) and let students know that we will be exploring these energy resources in more detail in the next lesson.
  • What kinds of energy are involved in a car moving down the road?  
    • This question allows you to debrief the activity on the energy conversions in a phone call while also checking students prior understanding of energy conversions with their hopefully more developed understanding following the lesson.  It's up to you which order to approach these examples, but I debrief the phone call activity first, then return to this question for the homework.  This example of student work shows a student's initial analysis of energy conversions in a car traveling down the road and shows that while they gave some consideration of the question, it could be fleshed out by more students offering their input.  
    • What I found useful was to draw a car on the board and just ask the class to offer examples of different types of energy being used and converted.  If necessary, you might want to go down the list of energy types (e.g., radiant, chemical, sound) and ask students if and how they are involved in the traveling car.  When students offer an example such as "the car's battery has chemical energy which is converted to electrical energy which the lights convert into radiant energy", I might draw a little battery in the engine and write the words "chemical", then draw wires and write "electrical",and have the wires connect to headlights where I write "radiant", and so on.  If students get stuck, I might ask, "what about kinetic energy?" which they will hopefully understand the car has simply by moving.  I would indicate this by drawing an arrow to represent motion and write "kinetic" over the arrow.  Again, the idea here with the car example and the cellphone activity is for students to think about the ways that energy is used and converted in everyday activities.