Curved mirrors are a student favorite! They see them in stores to help prevent five-fingered discounts. They see them on the rear-view mirror of cars. They see them on their make-up mirrors. They see them in novelty stores and shops as tools for creating odd visual effects. They even see them on their soup spoons. A unit on ray optics gives them an ability to understand them and their use. And part of that understanding involves understanding how and why the characteristics of the image that they see in a curved mirror depends upon the location of the object. And that is what this Concept Builder is all about.

Each question in the Concept Builder presents students with a mirror, a principal axis, and anobject arrow. Students must identify the characteristics of the image. They do so by tapping in one of the regions or locations outlined by a dashed rectangle; that selects the image location and orientation. They can then tap multiple times in that rectangle to toggle through the set of three possible sizes. Finally, they tap on the text field below the mirror to identify the type of images as being real or virtual. We have come to describe these four characteristics of images using the mnemonic LOST. The L is for location. The O is for orientation (upright or inverted). The S is for relative size (smaller, larger, or the same size as the object). And the T is for type (real or virtual). Our Tutorial pages on the topic are great preparations for this activity. We believe that a hands-on lab is an essential pre-cursor to this activity. Other great resources can be found in the Resources section below that supplement the use of this Concept Builder.

The Concept Builder includes five Question Groups with two questions in each group. If a student misses a question from a Question Group, the other question will eventually be presented to them. The paired questions ini each Question Group are different only in terms of which side of the principal axis that the red arrow object is on.

This Concept Builder was intended as an in-class activity. After some early lab investigation, some discussion and demonstrations of the rules of reflection for curved mirrors, allow students an opportunity to interact with the questions.  In order to complete the activity, a student must correctly analyze each Question Group. 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 the 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 que 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 of a difficulty level 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 levels.

In order to complete a level, a student must correctly analyze each question of 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 que 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 of a difficulty level 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 levels.

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 a few resources at The Physics Classroom website that serve as very complementary supports for The L•O•S•T Art of Image Description (Curved Mirrors) Concept Builder. These include:
 

• Reading:
  Most students will find that  Lesson 3 of the Reflection and the Ray Model of Light Chapter of the Tutorial is a perfect accompaniment to this Concept Builder. In particular, the following two pages will be most helpful:
  
  Ray Diagrams for Concave Mirrors
  
  Image Characteristics for Concave Mirrors
  
  
  
   
• Curriculum Corner
  The Curriculum Corner section of our website contains a complete course curriculum that coordinates with our Tutorial section and our Minds On Physics program. There are a few activities in the Reflection and Mirrors section that would be useful complements to this activity. These include:
  
  Ray Diagrams for Concave Mirrors
  
  Ray Diagrams for Convex Mirrors
  
  Visit Reflection and Mirrors section of the Curriculum Corner.
  
  
   

• Minds On Physics Internet Modules:
  The Minds On Physics Internet Modules include a collection of interactive questioning modules that help learners assess their understanding of physics concepts and solidify those understandings by answering questions that require higher-order thinking. Assignments RM6 and RM9 of the Reflection and Mirrors module are great complements to this Concept Builder. It is best used in the middle to later stages of the learning cycle. Visit the Minds On Physics Internet Modules.
  
  Users may find that the App version of Minds On Physics works best on their devices. The App Version can be found at the Minds On Physics the App section of our website. The Reflection and Mirrors module can be found on Part 6 of the six-part App series. Visit Minds On Physics the App.
  
  
   
• The Laboratory:
  There is no substitute for hands-on activities. And at The Physics Classroom, those hands-on activities can be found in The Laboratory section of the website. The following labs make useful pre-cursors to this Concept Builder.
  
  Exploring Curved Mirrors
  
  Finding Smiley
  
  Visit The Laboratory
  
  
   
• The Science Reasoning Center
  The Science Reasoning Center section of our website includes reading passages that describe experiments and data representations and present questions that force students to analyze the passages at a deeper level. There is one passage titled Concave Mirrors that can be found in this section that makes for a useful supplement to this activity.
  
  Visit Concave Mirrors
   

Additional resources and ideas for incorporating The L•O•S•T Art of Image Description (Curved Mirrors) Concept Builder into an instructional unit on Reflection and Mirrors can be found at the Teacher Toolkits section of The Physics Classroom website.  Visit Teacher Toolkits.