We're going to be honest: we do Physics. That's why this is called The Physics Classroom website. And when we do the Teacher's Notes section for our Concept Builders, we typically have a lot to say ... and a lot of resources to point you to. We're not claiming to be ignorant of chemistry; we just don't have a lot of resources here at The Physics Classroom to point you to. And so this page is going to be a lot shorter than our usual page that accompanies our Physics Concept Builders. That's our honest confession.

Most Chemistry and Physics courses include a considerable amount of attention to the use of the metric system. Units such as meters, grams, and liters are common-place within the course. And derivative units formed by adding Greek prefixes to such base units are also common. These units show up in labs, in discussions, and in problems. And particularly for students from the United States (where the metric system is still not adopted), such units are often troublesome, confusing, and hold little meaning. This Concept Builder addresses this issue, attempting to build students intuitive feel for metric units by challenging them to identify the mass, length, and volume of several common objects.

To improve student understanding and success, we think it would be helpful to place props around the room with labels. For instance, there could be a  250 mL beaker, a 5 mL graduated cylinder and a 100 mL graduated cylinder, a meter stick with cm and mm gradations, a 1-kg mass, a 50-g mass, etc. The goal of the Concept Builder is to help students develop an intuitive sense of the magnitude of basic metric units. Having such props available provides them with a reference point for thinking about each question. We also believe that the infographic which we have provided is a useful resource. Students can access it by tapping on the Help Me! button.

Each question in this Concept Builder presents the challenge of identifying the length, mass, and volume of an object. A photo of the object is displayed. Three answer options are given. Recognizing that there is a range of possible masses (or lengths or volumes) for an object such as an ant, an apple, an orange, etc., the answer options that are presented fall within the range. As such, students must draw upon their intuitive sense of how long a meter, a millimeter, a centimeter, and a kilometer are in order to select the correct answer. One of the answer options will be a rough estimate while the other two answer options are rather absurd. For instance, few students know the mass of an orange, but if they have a sense of how much a kilogram or a milligram of mass is, they will know that the mass of an orange is nowhere close to 400 kg or 0.004 mg. The Concept Builder builds on students' general sense of the magnitude of a milligram, centigram, gram, and kilogram.

Like all our Concept Builders, this Concept Builder utilizes a variety of strategies to make each student's experience different. The ordering of questions is random. The Question number assigned to each question is scrambled. For instance, two side-by-side students will not have the same question for question number three. And questions are organized into "groups" with questions within the same group being very similar (for instance, they have the same type of information as "givens") but not identical. And finally, the answer options are always scrambled.

The Concept Builder also keeps track of student progress. It requires that students demonstrate a mastery of questions in each Question Group. If they miss a question from one group, then they will have to answer two consecutive questions correctly in order to demonstrate mastery. Progress is displayed in the progress report on the right side of the Concept Builder. A star indicates a demonstration of mastery. A question with a red background indicates that the student has missed the question. And a question with a yellow background means that thestudent must get one more questoin from that Question Group correctly answered in order to obtain a star. When an activity is completed, the student will be awarded a Trophy. This Trophy is displayed on the Main Menu screen. These strategies make the Concept Builder an ideal addition to the 1:1 classroom and other settings in which computers are readily available. 

This Concept Builder consists of three distinct difficulty levels. The first level -  Apprentice Difficulty Level - has only 3 questions. Each question includes three answer options that have varying units but the same numerical values - for instance, 300 mg, 300 g, and 300 kg. Each time a question appears, the order of the answer options is scrambled. If students miss a question, a similar questio with a different set of units and/or numerical values will be presented. 

The second difficulty level - Master Difficulty Level - is similar to the Apprentice Level but contains 6 questions that are different than those used in the Apprentice Level. There s no redundancy between the two levels. The only attribute that makes the Master more difficult than Apprentice is the extra three questions. 

The third difficulty level - Wizard Difficulty Level - also includes six questions. However the answer options utilize different units and different numerical values. For instance, the mass of an apple may include options of 0.0025 mg, 250 g, and 2.5 kg.

In order to complete a difficulty 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.

While we typically feel that most Concept Builders are ideal as individual activities, this Concept Builder in particular could generate some awesome discussion among students when grouped together. As such, we would recommend this as a group exercise with the individual exercise being a possible follow-up to it.

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.