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 typical objective in the beginning of many chemistry courses is to construct the isotope notation for the atom. Such a notation or set of symbols communicates the elemental symbol that identifies the element, the atomic number, and the mass number. If the particle is an ion, then the charge on the ion is also communicated. Such an objective is typically addressed when the structure of the atom is introduced. The notation communicates information about the number of the three subatomic particles present in the atom - the protons, neutrons, and electrons. 

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 information as "givens") but not identical. And finally, the answer options for Multiple Choice questions are always scrambled.

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 thestudent must get one more questoin 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. 


This Concept Builder consists of three separate activities. The first activity -  Fundamental Concepts - has only 6 questions. Each question is a 5-option multiple-choice question that targets student understanding of key concepts associated with isotopes. These concepts (and definitions) include atomic number, mass number, ions, and the nature of a proton, neutron, and electron. Each time a question appears, the order of the answer options is scrambled.

The second activity - Isotope Symbols I - includes six Question Groups with three nearly identical questions in each group. Each question in every group demands that students create the isotope symbol for an atom of a given isotope. The symbol includes the elemental symbol, the atomic number, and the mass number. All atoms are electrically neutral.

The third activity - Isotope Symbols II - also includes six Question Groups with three nearly identical questions in each group. Each question in every group demands that students create the isotope symbol for an ion of a given isotope. The symbol includes the elemental symbol, the atomic number, the mass number, and the ion charge.


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.