At a Glance

Discipline

  • Physics

Instructional Level

  • College & CEGEP

Course

  • Electricity and Magnetism 203-NYB-05

Tasks in Workflow

Social Plane(s)

  • Group
  • Whole Class

Type of Tasks

  • Discussing
  • Analyzing
  • Presenting

Technical Details

Useful Technologies

  • Whiteboards

Class size

  • Small (20-49)

Time

Single class period (< 90 mins)

Overview

In this activity, students build a conceptual model for proton being launched towards a fixed, negatively charged particle. A “model” here refers to a coordinated set of multiple representations (diagrams, graphs, equations, words) which describe the physics involved.

The instructor begins class by explaining what a model is and why models are important to physicists. The instructor presents a familiar situation from Mechanics, for example an accelerating train.

The students then form groups of 4 and are assigned a whiteboard onto which they will present their model. Each group designates a note-taker who is responsible for copying down their group’s ...

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In this activity, students build a conceptual model for proton being launched towards a fixed, negatively charged particle. A “model” here refers to a coordinated set of multiple representations (diagrams, graphs, equations, words) which describe the physics involved.

The instructor begins class by explaining what a model is and why models are important to physicists. The instructor presents a familiar situation from Mechanics, for example an accelerating train.

The students then form groups of 4 and are assigned a whiteboard onto which they will present their model. Each group designates a note-taker who is responsible for copying down their group’s model onto a worksheet.

Students will need around 30 minutes to construct their model. As they work, the instructor’s role is to provide guidance and to ensure that the groups have included several appropriate representations.

Each group then pairs up with another one and they present their models to one another. The note-taker should add to their worksheet based on this discussion.

The activity ends with a class discussion during which the instructor asks students to share their reflections. The instructor concludes by re-iterating the motivation for the activity.

The instructor collects the worksheets and posts the best model online, along with comments.

It is important to emphasize model-building. Doing something once isn’t enough to build a skill. This requires repetition, reinforcement, and evaluation (this last point will motivate the students and also communicate the importance of this skill).

I like to do this at least one more time in class. I also have an evaluation specifically for model building. This could either be a homework to be passed in, or a quiz. A couple of possible scenarios to be modelled come to mind: (1) Similar to the worksheet: an electron is fired at a negatively charged bead from far away. (2) The motion of a charged particle in a parallel-plate capacitor.

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Instructional Objectives

Students learn to build a conceptual model describing a situation involving an accelerating charged particle.

Workflow & Materials

Activity Workflow

Download

Activity Instructions

Worksheet for Instructor Preparation

Download

Model Building

Link to CourseFlow Tool

Link

Contributor's Notes

Benefits

  • Using multiple representations improves students’ conceptual understanding and ability to solve problems.
  • To build a model, students must understand the relevant physics and be able to communicate that understanding. This prepares them to tackle any problem.
  • Because they are not solving a traditional physics problem, students cannot solely rely on equations to describe the situation. Instead, the activity teaches students to use multiple representations, the way a physicist would.
  • The activity re-enforces connections between concepts such as electric fields, electric potential, kinematics, forces, energy, etc.

Challenges

  • Students may forget to include essential representations such as equipotential lines. The instructor might need to guide students along to ensure that the class as a whole has a representative sample of all the desired representations.
  • Students may not be familiar with model building, and so it is important to explain why it is a valuable skill.

Tips

  • This activity should be performed at a point in the course where students have become familiar with several concepts in electrostatics.
  • A similar activity could be performed in Mechanics to expose students to model building earlier in their studies.
  • This activity is intellectually demanding for students. The final class discussion should be kept short.