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.

Students have great difficulty with the concept of molecular polarity. There is a lot involved - identifying a bond as polar or non-polar, writing a Lews electron dot structure, using VSEPR theory to determine a molecular geometry, and then deciding if the dipole moment vectors will cancel. That's numerous steps, neither one of which is of great comfort to many students. This Concept Builder (especially when combined with our Bond Polarity Concept Builder) comes to the aid of teachers attempting to convey these ideas. The Concept Builder puts an emphasis on the need to determine the molecular geometry as a precursor to deciding on the polarity of molecules. 

The Molecular Polarity Concept Builder is comprised of 54 questions organized into 18 Question Groups and spread across three different difficulty levels.  The Apprentice Difficulty Level includes 6 Question Groups and 18 total questions. Each question presents information about three molecules and students must decide if each molecule is polar or non-polar. The presented information includes the AXE notation, the molecular geometry, and a ball-and-stick model. The model provides a tremendous tool for helping students visualize the structure and the cancellation of any existing dipole moment vectors.

The Master Difficulty Level includes 6 Question Groups and 18 total questions. Each question provides a chemical formula and Lewis electron dot structure for a molecule. Students must determine the molecular geometry from the electron dot structure and then determine if the molecule is polar or non-polar. All structures are limited to a maximum of four electron groups around the central atom.  The Wizard Difficulty Level is similar to the Master Level with the exception that all structures have five or six electron groups around the central atom. Students must still determine the molecular geometry and the polarity of the molecule.

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 electron pair geometry) but not identical. 

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. 

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.