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.

Thermochemistry represents one more opportunity within the chemistry curriculum to revisit the importance of the coefficients in a balanced chemical equation. The components define the relationship between the moles of reactants and products and (in the case of thermochemical equations) the amount of energy released or absorbed by the system during the reaction. This Concept Builder provides three scaffolded activities to lead students through the process of implementing an understanding of stoichiometric relationships that pertain to energy. There are a total of 16 multi-part questions that have been organized into three levels of difficulty.

In the

**Apprentice Difficulty Level**, students complete five sentences, each of which has a numerical blank. The sentences start simple (real simple) and increase in difficulty. The emphasis is on gaining some comfort with the use of the equation to solve for an unknown. In the

**Master Difficulty Level**, students must complete a 5-row table with 2-3 blanks per row. Students must work with the mass-mole-kJ relationships to complete the table. The numbers presented in the table are mostly

*nice*. That is, they tend to be whole number multiples of the coefficients or the molar mass.The thermochemical equation represents the combustion of propane. The coefficients are relatively simple compared to the Wizard Level. In the

**Wizard Difficulty Level**, students must complete a 5-row table with 2-3 blanks per row. The thermochemical equation represents the combustion of butane; the coefficients are immediately more complicated than that of the Master Level. And the numbers presented in the table are no longer

*nice *whole number multiples of the coefficients.

The questions are shown on

a separate page (viewable by logged-in teachers only). Teachers are encouraged to view the questions in order to judge which activities are most appropriate for their classes and what level of preparation would be required. We recommend doing the activities in order. There is no redundancy in the actvitiies. While they are independent activities, they have been designed to be scaffolded such that one activity builds on the confidence that was derived from the previous activity.

Our Concept Builders typically utilize a variety of strategies to make each student's experience different. The main strategy employed here is to provide multiple tables for each level. A table is selected at random and presented to the student. This reduces the likelihood that two side-by-side students would have the same question.

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Students can complete as much of the table as they wish before checking their answers. And they can check their answers as many times as they wish. Feedback regarding the correctness of their answers is immediate and provided using a color-coding system. Correct answers are displayed in a table cell with a green background; these correct answers become

*locked* and cannot be changed. Incorrect answers are displayed in a table cell with a red background. Each time students check their answers, the number of missed answers is determined. A running tally is kept of the number of misses. When a student accurately completes the table, a Health rating is displayed on the screen. The Health rating is dependent upon the number of misses. Formulas for computing the Health rating are discussed

on a separate page. The Health rating is also displayed on the Main Menu screen for any completed difficulty level. A student can always repeat a difficulty level in order to improve their Health rating for that level. The best Health rating is always displayed on the Main Menu screen below the trophy for that difficulty level.

We leave it to the discretion of individual teachers as to what they wish to do with the Health rating information. We recognize that there will be some teachers who feel most comfortable with their students in simply requiring that a difficulty level be completed and trophy be earned. Other teachers may wish to require completion of a difficulty level with a minimum Health rating. For instance, such teachers may require that each difficulty level be completed with a 70% or higher Health rating. Still other teachers may tie the Health rating into a grade or allow a homework pass for completing an activity that exceeds a 90% Health rating. Decisions as to what to do with the Health rating are best left for individual teachers who know their students the best.

**Task Tracker Notice**: As of this writing we do not record Health Ratings in our Task Tracker database. It is for on-screen use only when used in the classroom in the presence of a teacher. The teacher can validated the Health Rating if desired.

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.