The Formulas and Atom Counting Concept Builder is an adjustable-size file that displays nicely on smart phones, on tablets such as the iPad, on Chromebooks, and on laptops and desktops. The size of the Concept Builder can be scaled to fit the device that it is displayed on. The compatibility with smart phones, iPads, other tablets, and Chromebooks make it a perfect tool for use in a 1:1 classroom.


Teaching Ideas and Suggestions:

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.

As we all know, the task of counting atoms of each element in a formula or set of formulas is an essential skill for a chemistry student. Atom counting is a pre-requisite skill for calculating molar masses and balancing chemical equations. Looking at a set of formulas and coefficients and making sense of them demonstrates some chemistry literacy. Yet the task of interpreting formulas is difficulty for many students and requires practice. This Concept Builder will provide that practice, give the necessary feedback, link to associated resources that provide help, and provide students with multiple opportunities for correction. 

There are three difficulty levels in the Concept Builder. They are designed to incrementally increase student confidence in interpretting symbolic representations of chemical systems and to count atoms. Those three levels are differentiated as follows:
  • Apprentice Difficulty Level: Question Groups 1-4 ... Each question includes only 1 formula with a coefficient. There are no parenthesis. Learners must count the number of atoms of two or three elements. 
  • Master Difficulty Level I: Question Groups 5-8 ... Each question includes 2 formulas with coefficients in front of each. Several of the formulas include parenthesis. Learners must count the number of atoms of three elements. 
  • Wizard Difficulty Level: Question Groups 9-12 ... Each question includes 3 formulas with coefficients in front of each. Several of the formulas include parenthesis. Learners must count the number of atoms of three to four elements. 

The questions from each group are shown on a separate page. Teachers are encouraged to view the questions in order to judge which difficulty levels are most appropriate for their classes. We recommend providing students two or more options. For instance you might say the Master Difficulty Level earns you an A and the Master and the Wizard together earns you Bonus Points. There is no redundancy in the Difficulty Levels. Each level gets progressively more difficult and every question in a difficulty level is unique to that level.

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. And 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 may contain the same formulas but have different coefficients) 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. 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 other question in the Question Group and then returrn to the originally-missed question in order to successfully complete the difficulty level. This approach provides the student extra practice on questions for which they exhibited difficulty. As a student progresses through a difficulty level, 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 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.