# Charge Fundamentals

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## Objective

Students will be able to define the law of charges, differentiate between conductors and insulators, and explore methods of charge transfer.

#### Big Idea

After students define key components of charge, they virtually explore charge transfer with a computer simulation.

## Context

This electrostatics and electricity unit starts with an introduction of charge and charge transfers (HS-PS1-3). The goal of the lesson is to give students an overview of how charged particles interact with each other and the properties of charge transfer. The lesson starts with a video introduction before students actively take notes. Today's notes include defining the properties of charge, identifying the law of charges, exploring the difference between conductors and insulators, and differentiating between the methods of charge transfer. Students apply their newly learned knowledge using a simulation that models charge transfer due to rubbing (SP2 & SP4).

## Introduction with an Electrostatics Video

10 minutes

Because there are so many resources on the internet, I decide to use this video to introduce static electricity to my students. We just finished a unit on sound, so today I want to capture students' attention and show them several different demonstrations that involve charges. It is the goal of this video to show students that static electricity is around them and part of their lives on a daily basis.

Before I start the video I make sure my expectations are clear: students need to be sitting quietly, listening and watching the video, and taking notes on meaningful material. To me, meaningful material includes any reference to previously learned concepts, vocabulary, and the results of the different demos. While I do not collect their notes, these are an essential resource as students take notes and then work through the simulation. I am telling my students these expectations as I'm on my way to start the video.

## Charge Fundamentals PowerPoint

25 minutes

It's time for students to take out a sheet of paper and get ready to learn about the characteristics of electrostatics. My students are operating under the expectation that they must write down key concepts of the presentation. This expectation of how to take notes has been outlined and ingrained in their learning since freshman year.

I display the Charge Fundamentals PowerPoint (also available as a PDF) to help the students understand what they need to write down. As I'm showing the slides on the front board, I have a hard copy of the PowerPoint which includes teacher notes (viewable when the file is downloaded). These notes help me to stay focused and ensure I mention the highlights as we progress through each slide.

The presentation starts with an explanation of charge properties, including the law of charges and the law of charge conservation. Then, students learn the amount of charge electrons and protons contain before comparing conductors and insulators. Once students are familiar with materials that act as good conductors and insulators, they are then introduced to three methods of charging: conduction, induction, and polarization. These notes give students an opportunity to qualitatively define the methods of charging with visuals.

While I describe this section as "direct instruction," I usually have a lot of interaction with my students throughout the presentation and am constantly moving throughout the room to change my proximity. The students ask questions and connect to real-world examples to stay engaged the entire time. In this particular set of notes, students contribute some great examples of how polarization is present in their daily lives. One student in particular shares how she was mortified a day at lunch when she couldn't detach a snack wrapper from her hand while trying to throw it out.

## Charge Simulation Activity

15 minutes

After we've finished watching the video and taking notes, the lesson ends when students use a computer simulation that allows them to be more active in their learning. The simulation allows students to visualize common static electricity concepts. Specifically, students start by observing the initial arrangement of charges on a balloon, sweater, and wall. Then, students rub the balloon on the sweater and describe how the charge distribution changed. After thinking about why the charge distribution changed, students bring the charged balloon near the wall and describe their observations. The simulation activity ends when students create situations in which the balloon is in equilibrium.

Before we start the activity, I assign partners using the random student generator that already has my students' names loaded. By displaying the random generator on the front board, there is an element of suspense as the partners are assigned. Partners work best for this activity so that each student can be actively engaged throughout the work time. Because this activity does not need to be completed outside of class, I feel comfortable in choosing the pairings for my students.

We use MacBook Pro's in my district, so my students are familiar with how the computer and cart organization works. After each pair has been assigned, the students move to sit near each other, push their desks together, and grab a computer. As the computers are booting I pass out the charge simulation activity so that each student receives a copy. This document directs them to PhET where they will be using the balloons and static electricity simulation. The activity sheet is also meant to direct the students in their learning so that they are confident in what material needs to be understood.

While students are working, I walk around to ensure they are actively engaged in the learning process. This means that they are on the proper website, reading or discussing some component of the simulation, and writing down appropriate information from the simulation. When I walk around, I'm spot checking their written work and engaging students in questions such as "What did you notice about the charge's alignment?" or "Were you able to get a balloon to 'float' yet?"

The students' written answers are the most important part of this activity, so I ensure they are thinking through how they will prove any claims they make. I do a lot of walking and questioning throughout their work time to ensure they can justify anything that has been written down. The AP Physics 1 exam places a lot of emphasis on justifying thought processes and writing, so my goal in our dialogue is to practice with students how to successfully justify their arguments.

When there is approximately 5 minutes prior to the end of class, I ask students to put the computers back on the cart and return to their seats. I also tell them at this point that the lab is due at the start of the next class meeting.