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.

A large portion of any chemistry course will pertain to chemical reactions. An essential skill for this is the skill of being able to write and balance a chemical reaction. This Concept Builder focuses on that skill, with an emphasis on using an understanding of reaction types in order to translate word equations into balanced chemical equations. The Concept Builder will target student comfort and skill with the following:

There are 36 total questions organized into 18 different Question Groups and spread across three activities. Those three activities can be described as follows:
 

• Predicting Products: Question Groups 1-6 ... Students are presented with a verbal description of a reaction that uses reaction type words like combustion, synthesis, decomposition, single replacement, and double replacement. They must use what they know about these reaction types in order to predict the chemical formula of the products.
• Writing Chemical Equations 1: Question Groups 7-12 ... Students are presented with a verbal description of a reaction. They must identify the chemical formulae for the reactants and products. Then they must insert coefficients in front of the formula to balance the equation. The reactions include one decomposition, one double replacement, and four synthesis reactions. 
• Writing Chemical Equations 2: Question Groups 13-18 ... Students are presented with a verbal description of a reaction. They must identify the chemical formulae for the reactants and products. Then they must insert coefficients in front of the formula to balance the equation. The reactions include two combustion, two double replacement, and two single replacement reaction types. 

Teachers are encouraged to view the questions in order to judge which activities are most appropriate for their classes. 

The first activity will require that students be able to identify the products for decomposition reactions (1 Q), hydrocarbon combustion reactions (1Q), single replacement reactions (2 Qs), and double replacement reactions (2 Qs). The second activity will require that students be able to write balanced equations for synthesis reactions (4 Qs), decomposition reactions (1 Q), and double replacement reactions (1 Q). And the third activity will require that students write balanced equations for hydrocarbon combustion reactions (2 Qs), single replacement reactions (2 Qs), and double replacement reactions (2 Qs).

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 may include the same number of coefficients and required elements to balance.

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 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. 


In order to complete a difficulty level, a student must correctly analyze each question of that difficulty 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 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. 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 difficulty levels.

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.