### Notes:

The Cell Voltage 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.

One common objective in an Electrochemistry unit is to determine the cell voltage of a galvanic cell using a table of Standard Reduction Potentials. This Concept Builder targets this objective by providing 24 questions that step students through the process of determining the two half-equations and their potential and the overall cell potential. The 24 questions are organized into 12 Question Groups and spread across three difficulty levels. The levels are independent of one another, allowing a student to jump in at any level and to exit at any level. There is little variation in difficulty between the difficulty levels. They should be thought of as additional examples to practice with.

Here is the breakdown of the difficulty levels:
• Apprentice Difficulty Level: Question Groups 1-4 ... Students are given contents of each half-cell and must use a table of standard reduction potentials to determine the reduction and oxidation half equations and their potential and the overal cell voltage.
• Master Difficulty Level: Question Groups 5-8 ... Students are given contents of each half-cell and must use a table of standard reduction potentials to determine the reduction and oxidation half equations and their potential and the overal cell voltage.
• Wizard Difficulty Level: Question Groups 9-12 ... Students are given contents of each half-cell and must use a table of standard reduction potentials to determine the reduction and oxidation half equations and their potential and the overal cell voltage.

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

There are 2 similar questions in every Question Group. The half-cells contain the same components but are simply reversed from left to right. If a student misses a question from within a particular Question Group, then they will have to answer both questions correctly (without any further miss). This strategy provides students extra practice on their most troublesome questions.

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"; the question a student receives is selected at random. In the end, two side-by-side students will likely have quite different experiences.

For those with Task Tracker accounts, 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.

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.