The Which One Doesn't Belong? - Energy and Chemical Reactions 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.

Energy is a central topic in all subject areas. In Chemistry, one common goal is for students to understand the connection between energy and chemical change. This goal has many dimensions, but one is to be able to distinguish between endothermic and exothermic processes. Teachers represent these processes in a variety of ways. First, there are the definitions. For instance, endothermic reactions are often defined as reactions in which energy is absorbed by the system from the surroundings. On the other hand, exothermic reactions are often defined as reactions in which energy is released from the system to the surroundings. These definitions are often illustrated using a system-surroundings diagram; the system is the reactant and product chemicals and the surroundings is everything else. As the reaction takes place, there is a transfer of energy across the boundary separating the system (chemicals) and the surroundings. Energy level diagrams are also used to provide a graphical representation of endothermic and exothermic processes. The energy level of reactants and products are plotted on a graph and labeled. Reactant energy levels are less than or greater than the product energy levels, depending upon whether the reaction is endothermic or exothermic. Symbolic representations include thermochemical equations in which an energy term is included in the equation along with the formulas of reactants and products. An enthalpy change (∆H) value is often used as a numerical representation, with a + value being used for an endothermic reaction and a - value being used for an exothermic reaction. And finally verbal representation can describe the transfer of energy or the change in temperature of the surroundings or a comparison of the energy of reactants and products. This Concept Builder targets student understanding of endothermic and exothermic processes and their representations.

The Concept Builder includes three difficulty levels with four unique Question Groups in each difficulty level. There are three similar questions in every Question Group. If a student misses a question from within a particular Question Group, then they will have to answer two different questions correctly (without any further miss) from that same Question Group. This strategy provides students extra practice on their most troublesome questions. The questions can be viewed on a separate page. The three difficulty leves are differentiated as follows:
  • Apprentice Difficulty Level: Question Groups 1-4 ... Each question includes three representations. One of the representations states whether the reaction is endothermic or exothermic.
  • Master Difficulty Level: Question Groups 5-8 ... Each question includes four representations. One of the representations states whether the reaction is endothermic or exothermic.
  • Wizard Difficulty Level: Question Groups 9-12 ... Each question includes four representations. 

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 type of representations) 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 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 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.