# Quantitative Conservation of Energy, Part 2

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## Objective

Students will be able quantitatively apply the law of conservation of energy to various situations.

#### Big Idea

Students investigate the relationship between conservation of energy and a common toy, the popper.

## Quantitative Conservation of Energy Whiteboard Session

35 minutes

The goal of this lesson is to give students another day to work through the ideas of quantitative conservation of energy (HS-PS3-1). During this lesson, students use models to complete problems (SP2) as well as computational thinking to get to the answers in each activity (SP5). During the whiteboard sessions, students communicate to the class their thought process during the problem-solving they did to complete the quantitative conservation of energy problems (SP8).

To begin class, I have students pull out their Quantitative Conservation of Energy Problem WS that they worked on in class and finished for homework. I have students select a playing card for their group to decide which problem they will be whiteboarding in front of class. I have playing cards A-7 and each group selects a card which tells them what problem they are in charge of (ex. A = problem #1, 2 = problem #2, etc.). Once each group has their assigned problem from the playing cards, they grab a whiteboard and show all of their work. I give them about 5 minutes to prepare their whiteboard.

When the class is ready for presentations, I select two students randomly using the seat numbers on their tables and a die to present their problem. I do this so that everyone in the group must know what is going on in the problem and cannot "hide" within the group. During presentations, I ask the presenters to read the problem and then explain their thought process. Below you can see some examples of student whiteboards.

The audience members check their work and ask questions at the end of the presentation if they do not agree with what is on the whiteboard.  If no students ask questions, I make sure to ask at least one question to the group before they sit down.

## Conservation of Energy Popper Activity

25 minutes

After the whiteboard session, I have students work with a partner to complete the Popper Lab Activity. This is one of my favorite activities to do with the students because the love to play with the poppers (shown below).

Students work with the person sitting next to them on this activity. Each pair gets one popper and two meter sticks. One partner is in charge of holding the meter stick(s) to measure the height. The other partner is in charge of flipping the popper and recording the height that the popper reaches. Students collect data for multiple trials and then find an average height from that data that is recorded on the Popper Lab Activity

After students collect all of the data, they work on completing the analysis questions found in the handout. The questions focus on students determining the potential and kinetic energies at specific points and equations as well as the concepts of conservation of energy. As students are working, I walk around to make sure they are collecting data correctly and to answer questions if they have them. I like to do this activity because it is another lab experience that gets students to see the relationship of potential energy at the highest point and kinetic energy at the lowest point and how conservation of energy plays into that.

## Conservation of Energy Checkpoint

10 minutes

To end class, I have students complete the Conservation of Energy E.O.D Checkpoint. Since students have had limited time with this difficult concept, I have students complete this checkpoint as a group. I expect students to be able to work as a group to solve the multi-step quantitative conservation of energy problem. I tell students that I need to see all work for each quantity they solve for. I collect this checkpoint and grade it to return in the next class period.

As you can see in the student samples below, the top group struggled with this problem. They forgot that the total energy at each location is equal to the sum of the kinetic energy and potential energy at that point. The bottom group was able to recognize that as well as the bottom location has all kinetic energy and the top location has all potential energy.