In many schools, chemistry or physics is the first quantitative science course that students encounter. And these courses tend to be the first courses demanding a comfort and reliance upon metric units and conversions and the use of such units in lab measurements. As such, most chemistry and physics courses include an objective early in the course associated with the use of the metric system and the acquisition of some comfort with base units and Greek prefixes. In most lab contexts, one can typically expect to utilize units that include the Greek prefixes milli-, centi-, and kilo-.This Concept Builder is designed to provide some practice and assessment of student understanding of the metric system and the use of these three Greek prefixes. The Concept Builders includes three distinctly separate activities. Those three activities are differentiated as follows:
 

• Milli-, Centi-, and Kilo-: Question Groups 1-3 ... Students identify the meaning of the prefixes milli-, centi-, and kilo- and use that meaning to relate a measured quantitiy expressed with that prefix to the equivalent amount of the base unit.
• Matching Pairs: Question Groups 4-5 ... Eight quantities are given; students must identify the four pairs which are equivalent to one another.
• Ranking Tasks: Question Groups 6-8 ... Students rank three different quantities (all having the same base unit) according to their relative size.

The questions from each group are shown on a separate page. Teachers are encouraged to view the questions in order to judge which activities are most appropriate for their classes. We recommend doing the activities in the order in which they are presented as they are scaffolded in such a manner that one builds upon the other. We also recommend that teachers do each activity to gain a feel for the level of cognitive rigor required of the student. 

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 target the same concept) but not identical. And finally, the answer options for Multiple Choice questions 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. In order to complete a activity, a student must correctly analyze each question of that activity. If a student's analysis is incorrect, then the student will have to correctly analyze two other questions in the Question Group in successive fashion 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 activity. 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 the student must get one more question 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. 

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.