Many Physics courses include a unit on Static Electricity. For such courses, the process of polarization will be an essential idea for explaining many electrostatic phenomenon. Students have a difficulty time with what polarization is and isn't. This Concept Builder addresses the concept of polarization with three different activities - Separation of Charge, Particle Flow, and Induction. We recommend its use at or near the midpoint of a unit on Static Electricity. 

The third activity of the three addresses a related topic - the charging by induction process. Teachers may differ on its usefulness and importance. We believe that it is a useful activity for helping students make meaning of how objects become charged by induction. It is a natural extension of the understanding of polarization.

This Concept Builder consists of 38 different questions that are grouped into 19 different Question Groups and spread across three different activities. Those three activities are described as follows:

• Charge Separation: Question Groups 1-4. Each question depicts a situation in which a charged object is brought near a neutral, conducting object. Students must decide how positive and negative charge within the conductor distributes itself. They must also identify the proper words that desribe the conductor, choosing as many that apply from among positively-charged, negatively-charged, electrically neutral, and polarized.
• Particle Flow: Question Groups 5-12. Each question describes a physical situation in which a charged balloon is brought near a series of neutral, conducting and connected blocks. Some of the blocks are conductors; others are insulators. Learners must decide how charge rearranges itself on the blocks in the precence of the charged balloon. They must also identify the manner in which particles (protons, electrons) within the block move in oroder to cause such a distribution.
• Induction  Question Groups 13-19. Each question describes and animates a common electrostatic procedure in which a charged object is brought near to a neutral, conducting object in order to induce the movement of electrons within the neutral object. The neutral object is then touched by a hand in order to cause the movement of electrons between the object and the hand - in one direction or the other. Learners must identify the resulting charge on the object that was originally neutral and explain the charge in terms of particle movement.

Before using the Concept Builder with your classes, we recommend that teachers attempt each of the activities in order to determine which are most appropriate for your classes and what pre-requisite understanding a student must have in order to complete it. Alternatively, the questions are provided in a separate file for preview purposes. Our suggestion is to assign the first two activities earlier in the unit and to assign the third activity once a discussion of charging by induction has begun.

In order to complete an activity, a student must correctly analyze each question in that activity. If a student's analysis is incorrect, then the student will have to correctly analyze the same or very similar question twice in order to successfully complete the activity. This approach provides the student extra practice on questions for which they exhibited difficulty. As a student progresses through an activity, a system of stars and other indicators are used to indicate progress on the level. A star is an indicator of correctly analyzing the question. Once a star is earned, that question is removed from the queue of questions to be analyzed. Each situation is color-coded with either a yellow or a red box. A red box indicates that the student has incorrectly analyzed the question and will have to correctly analyze it twice before earning a star. A yellow box is an indicator that the question must be correctly analyzed one time in order to earn a star. Once every question in an activity has been analyzed, the student earns a Trophy which is displayed on the Main Menu. This system of stars and trophies allows a teacher to easily check-off student progress or offer credit for completing assigned activities.

The most valuable (and most overlooked) aspect of this Concept Builder is the Help Me! feature. Each Question Group is accompanied by a Help page that discusses the specifics of the question. This Help feature transforms the activity from a question-answering activity into a concept-building activity. The student who takes the time to use the Help pages can be transformed from a guesser to a learner and from an unsure student to a confident student. The "meat and potatoes" of the Help pages are in the sections titled "How to Think About This Situation:" Students need to be encouraged by teachers to use the Help Me! button and to read this section of the page. A student that takes time to reflect upon how they are answering the question and how an expert would think about the situation can transform their naivete into expertise. 

 

 

There are numerous resources at The Physics Classroom website that serve as very complementary supports for the Polarization Concept Builder. These include:
 

 

 

Additional resources and ideas for incorporating this Polarization Concept Builder into an instructional unit on Static Electricity can be found at the Teacher Toolkits section of The Physics Classroom website.  Visit Teacher Toolkits.