Let it Go!

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Objective

Students will demonstrate an understanding of gravitational potential energy by analyzing data they collect during a set of hands-on activities.

Big Idea

Gravitational Potential Energy is the energy associated with an object's position in a gravitational field.

Overview

The goal of this lesson is for students to demonstrate their understanding of gravitational potential energy and kinetic energy by creating a claim using evidence they gather from a set of hands-on activities. This lesson addresses the HS-PS3-2 standard because it asks students to quantify the change of kinetic energy to potential energy at three distinct points during a pendulum's motion. It aligns with the NGSS Practices of Planning and Carrying Out Investigations (SP3),Using Mathematical and Computational Reasoning (SP5), and Constructing Explanations (SP6) because students will create and analyze a set of data that shows trends in the potential and kinetic energy of pendulum at three distinct points in its motion.

Within this lesson, students use a simulation and a spreadsheet to analyze the energy of motion and position of a pendulum. Students work in groups of four to create a claim about the gravitational potential energy of a pendulum. Finally, students sketch the energy make-up of a pendulum during different points of its motion that highlight their understanding of the gravitational potential energy of a system. Within this lesson, I ask students to focus on communicating their current understanding of gravitational potential energy. I assess student understanding throughout the lesson using informal check-ins and assess each student's work at the end of the school day on a scale of 1 (Advanced Beginner) to 5 (Highly Proficient).

Bell-ringer

5 minutes

This portion of the lesson follows a routine to communicate the ideas that students need to be proficient in by the end of the semester and it also highlights the goals of the lesson to students. I summarize the key ideas through the bell-ringer activity and take attendance while students transfer the projected information into their notebooks.

Today's additional piece of information is a BIG IDEA which states that gravitational potential energy is the energy that is stored due to an object's position. Later on within this lesson I ask students to use a simulation to investigate the effect of mass and length on the period of a pendulum.  In this lesson, I want students to work in small groups and use information gathered from hands-on activities to construct explanations for gravitational potential energy.

PhET: Pendulum Lab

40 minutes

After students complete the bell-ringer, I spend the first five minutes of this section distributing Chromebooks to students who are sitting in groups of four. It takes a little longer for some students to get started than others, but after five minutes or so most students divvy up the work and begin.

During the next thirty-five minutes, I project the directions for this activity on the interactive whiteboard at the front of the room for students to complete. Students work in teams of four writing their observations in their lab notebooks. I project these requirements on the board and ask students to:

  • Answer the focus questions
  • Generate Excel Data
  • Answer the analysis questions

During this section of the lesson, students use this simulation to investigate the effect of angle and mass on the gravitational potential energy of a pendulumThe purpose of this assignment is to have students use information from a hands-on activity to make a claim about the potential energy of a pendulum during one full period. During this activity, students work in teams to collect data, generate tables and charts in  Excel, analyze that data, and answer a set of analysis questions to determine which variable affect the potential energy of the pendulum. As students are using the simulation, I walk around checking in with them. At the end of this section, I pause and ask students to return the materials to the front resource station.

Calculating Kinetic and Potential Energies for a Pendulum

20 minutes

I spend the first five minutes of this section distributing a meter stick, a bob, string, a retort stand, and a timer to students who are sitting in groups of four. Students use these materials to investigate the mechanical energy of a pendulum at three distinct locations. Students calculate the gravitational potential energy and kinetic energy for a pendulum at three locations during a single period. It takes a little longer for some students to get started than others, but after five minutes or so most students divvy up the work and quickly get to the task at hand.

During the next thirty minutes, I project the requirements for this activity on the interactive whiteboard at the front of the room for students to complete. Students work in teams of four writing their observations in their lab notebooks.

I project these requirements on the board and ask students to:

  • Show the calculation the gravitational potential energy and kinetic energy of a Pendulum for three distinct locations
  • Include Essential Question(s) which I post on a bulletin board on the left side of my classroom
  • Illustrate the energy of each system using bar graphs for each location of the pendulum
  • Make a claim about the gravitational potential energy of a pendulum

As students are working on their experiments, I walk around checking in with them. Some student claims include, "The potential energy of a pendulum is equal to the total energy at the beginning of its period", and "The potential energy of a pendulum is zero at the equilibrium position". The purpose of this assignment is to have students use information from a hands-on activity to make a claim about gravitational potential energy. At the end of this section, I pause and ask students to return the materials they used during this section to the front resource station.

Closure

10 minutes

The closure activity this section asks students to sketch the motion of a pendulum and qualitative bar graphs of the kinetic and potential energy of the pendulum at three distinct points during a single period. Students choose the pendulum points. This type of closure activity asks students to communicate their understanding of the connection between pendulum motion and energy. Click here to see an example. 

I choose this type of activity to give students the opportunity to illustrate their current level of understanding of energy changes based on the position and motion of a pendulum. To wrap up this section of the lesson, I ask students to complete the physics classroom tutorial on work and energy before the next lesson.