The Case Studies - Electric Power Concept Builder targets student understanding of the variables that effect the power or wattage of a light bulb in a simple circuit. Students will have to understand the relationships between power, battery voltage, current, and resistance to be effective in this exercise. The Concept Builder is comprised of 36 questions. The questions are divided into 18 different Question Groups. There are two questions in each Question Group; questions in the same group are rather similar to one another. The Concept Builder is coded to select at random a question from each group until a student is successful with that group of questions.

This Concept Builder consists of three different difficulty levels. Those three activities are described as follows:
 

• Apprentice Difficulty Level: Question Groups 1-6. Two circuits are given; there is only one stated difference between the two circuits. Students must determine in which circuit the light bulb is brightest.
• Master Difficulty Level: Question Groups 7-12. Two circuits are given; there are two stated differences between the two circuits. Students must determine in which circuit the light bulb is brightest.
• Wizard Difficulty Level: Question Groups 13-18. Two circuits are given; there are two stated differences between the two circuits. Students must determine in which circuit the power is greatest and by what factor it is greaterst..

The questions from each group are shown below. Teachers are encouraged to view the questions in order to judge which activities are most appropriate for their classes. We recommend providing students two or more options. 

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. 

In order to complete a level, a student must correctly analyze each question in that level. 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 level. This approach provides the student extra practice on questions for which they exhibited difficulty. As a student progresses through a level, 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 cue 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 Case Studies: Electric Power Concept Builder. These include:

 

 

Additional resources and ideas for incorporating this Case Studies: Electric Power Concept Builder into an instructional unit on Electric Circuits can be found at the Teacher Toolkits section of The Physics Classroom website.  Visit Teacher Toolkits.