There are two essential ingredients that are responsible for much of the color of our world. First, our eyes are sensitive to a small range of wavelengths within the electromagnetic spectrum. Each of these wavelengths is associated with a color. When light of a specific wavelength or range of wavelengths reaches our retina, we perceive the color or colors associated with that/those wavelength(s). Second, the objects around us contain pigments that selectively absorb a wavelength or range of wavelengths. These pigments subtract out some color by absorption, preventing such wavelengths of light (and associated color) from reaching our retina. The pigments can be a natural constituent in the things around us or something that humankind has manufactured and added to the objects around us. 

This Concept Builder is designed to help students refine their understanding of the relationship between the incident light, the pigments present in an object, the appearance of that object when viewed in the presence of the incident light. There are three independent activities. Each activity has a different emphasis. A teacher using this Concept Builder with their classes can choose to do all three activities or pick and choose from among them. There is no need for a student to have completed Activities 1 and 2 before doing Activity 3. 

There are a total of 33 questions in this Concept Builder. The questions are organized into 15 Question Groups. Questions in the same group are very similar to one another. The three activities are differentiated as follows.
 

• Name That Pigment: Question Groups 1-6 ... Learners identify the pigment present in a sheet of paper from observations of the papers color appearance when two different light colors shine upon it.
• Fashion Show: Question Groups 7-12 ... Learners determine the color appearane of a shirt when they are given the pigments that it contains and the incident light color.
• Gum Drops: Question Groups 13-15 ... Learners determine the printer inks - cyan, magenta, and/or yellow - that must be applied to various parts of a color image in order to produce the desired results.

 
Teachers using the Concept Builder with their classes should preview the activity (or view the Questions in the separate file) in order to judge which activity would be most appropriate for their students. 

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 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 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 a numerous resources at The Physics Classroom website that serve as very complementary supports for the Color Pigments Concept Builder. These include:
 

• Reading:
  Most students will find that  Lesson 2 of the Light Waves and Color Chapter of the Tutorial is a perfect accompaniment to this Concept Builder. In particular, the following three pages will be most helpful:
  
  Light Absorption, Reflection, and Transmission
  
  Color Addition
  
  Color Subtraction
  
  
   
• 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 Light and Color section that would be useful complements to this activity. These include:
  
  Reflection, Transmission and Color
  
  Color Addition and Subtraction
  
  Viewed in Another Light
  
  Pigments and Paints
  
  Visit Light and Color 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 LC4, LC5, LC6, and LC7 of the Light and Color module are great complements to this Concept Builder. They are 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 Light and Color module can be found on Part 5 of the six-part App series. Visit Minds On Physics the App.
  
   

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