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 balance a chemical reaction. Many Chemistry courses give attention to the task of classifying a reaction according to its type. The five basic types of reactions are synthesis, decomposition, combustion, single replacement, and double replacement. Being able to classify a reaction according to type is often times a pre-cursor to being able to translate a word equation describing a chemical reaction into a balanced chemical equation. This Concept Builder provides students with an exercise in recognizing the type of chemical reactions for a variety of chemical equations.

The Concept Builder includes 39 questions organized into 18 different Question Groups and spread across three activities. Those three activities are described as follows:
 

• Reaction Type Fundamentals: Question Groups 1-8 ... Students are presented with a skeleton equation. They must enter coefficients in order to balance the equation. Each time a coefficient is changed, an Atom Count panel is updated. The panel shows the number of atoms of each element on reactant and product side of the equation. 
• Name That Type: Question Groups 9-14 ... Students are presented with three balanced chemical equations. By inspecting the equations, they must be able to identify the reaction type of each. They tap on a button to select their answers.
• Wizard Difficulty Level: Question Groups 15-18 ... Students are presented with five balanced chemical equations, one from each reaction type category. By inspecting the equations, they must be able to identify the reaction type of each. They drag and drop a reaction type label onto the equation.

Teachers are encouraged to view the questions or do the Concept Builder in order to judge which difficulty levels are most appropriate for their classes. 

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. In the first activity, the order of answer options is randomized each time the question is delivered to the student's screen. And questions are organized into "groups" with questions within the same group being very similar.

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 an 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 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 activities.

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.