Electrostatic Charge Stations

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Objective

Students create charge diagrams based on their observations at a variety of stations with electrostatic activities.

Big Idea

Charge stays in place on an insulator and charge is free to move around on a conductor.

Context and Supplies

This lesson, students rotate between 7 stations. The primary objective at each station is to observe the behavior of the charged objects at each station and draw a charge diagram based on that observation.  

The seven stations require the following supplies.

  • Station 1 - The can quiver: Rabbit fur, a plastic tube and an aluminum can
  • Station 2 - Packing peanuts: Rabbit fur, a plastic tube and styrofoam peanuts
  • Station 3 - Two hanging Balloons: two balloons filled with air, rabbit fur, strings and stands to hang the balloons from.
  • Station 4 - Single Balloon: Balloon
  • Station 5 - Charge by Induction:  Hewitt’s Conceptual Physics textbook.
  • Station 6 - Water polarization: plastic cup with a whole on the side, near the bottom, a balloon and rabbits fur.
  • Station 7 – Electroscope: an electroscope, rabbit fur and a plastic tube

Applied NGSS include Science Practice 1: Asking questions about their observations and Science Practice 2: Developing and using models where students draw charge diagrams. Given the supplies, students also apply Science Practice 3: Planning and carrying out investigations, Science Practice 6: Constructing explanations and Science Practice 7: Engaging in argument from evidence. CCSS Math Practice 3: Construct viable arguments and critique the reasoning of others is also involved.  This is all in the context of NGSS performance standard HS-PS2-4: Use mathematical representations of Newton’s Law of Gravitation and Coulomb’s Law to describe and predict the gravitational and electrostatic forces between objects.

Introduction to Electrostatic Charge Stations

5 minutes

Before class begins I set up the seven stations described on the Station Description Sheets. I also put a description sheet at each station. Then I project a count-down timer which is on my computer and set to 5:25 on the board.

At the start of class, I tell the students that today they experience a variety of charged objects. They are to play around with the situations and construct an explanation of what they observe by making a series of charge diagrams like they learned in All Charged Up. They also answer questions and construct explanations on what they observe. They have 5 minutes per station plus 25 seconds to transition from one station to the next. 

I want to set up heterogeneous groups of four, so I count the number of students in the class and divide that number by 4. For example, if I have 28 students, then there are 7 groups. I go around the room and have students count off, 1-7. I instruct all 1s to go to station 1, etc. This method creates random grouping which tend to be heterogeneous.

Once the students are in their groups, I hand out the Station Write-Ups. On the sheet there are rolls for each student to perform so that all students have a responsibility that helps the whole group succeed. Also, they should change rolls from one station to the next. I start the timer and instruct the students to begin at their current station. 

Students Experiment at the Electrostatic Charge Stations

40 minutes

While students engage with the items at each station, I circulate the room and observe them to make sure students are on task. I also want to help when there are questions. I usually answer one of their questions with a question of my own as I try to lead them to their own explanations. It is great to watch the students figure out how to make things move without direct contact, such as the Can Quiver station, the water attraction station and the two balloons station.

The timer is set to loop, so I don't have to do anything at the front of the room. Students are self-directed throughout this activity. I just walk around and watch the students work. If I see an example of exemplary work, I put a star right on the student handout. For the work that shows misunderstandings, I ask leading questions on why they believe their answer is correct.  For instance, if they show two objects sticking together but with the same charge, I ask them what happens when you bring like charges together. 

If I see multiple groups with the same errors, I grab a sample and take a picture of it with my document camera for review at the end of the class.

Closure

5 minutes

At the end of the station work, students return to their original station. I let students know that it is ok for them to correct any misunderstandings they have while we look at some samples.  I display some of the common mistakes that I see and ask students to explain what is wrong with the diagram. For instance, with this balloon diagram, the charge is spread out over the balloon surfaces as though they were conductors, but they are insulators, so the charge will stay where the fur was wiped. Or this can diagram shows the can as having a net charge, but it does not. The can should be neutral. I ask more questions to get students to explain that the charge on the can becomes polarized due to the rod being near it. As students exit, I collect their work for assessment. For the next lesson, we review the students' work.