Notes

This Concept Builder is designed to be used early in a unit on rotational kinematics. The emphasis is on angular acceleration. Students will need to relate an angular acceleration to a change in angular velocity. There are three main aspects of therelationship that are addressed. First, a rotating object has an angular acceleration if its angular velocity is changing. Second, students must relate the sign of the angular acceleration to the direction of motion and whether the object is speeding up or slowing down. And finally, students must use initial and final angular velocity values and a time change to determine the angular acceleration value.

This Concept Builder consists of 40 different questions that are organized into 13 different Question Groups and spread across three different activities. Those three activities are described as follows:

• Getting the Angle on Acceleration Question Groups 1-6: Students are provided words, a graph, or a table of data and must use the information to decide if an object is experiencing an angular acceleration or not.
• +, -, or 0 Question Groups 7-9: Students are given information about the clockwise or counterclockwise motion of a rotating object and whether it is slowing down, speedinig up, or moving at a constant speed; they must identify the angular acceleration as being either positive, negative, or zero.
• Crunch the Numbers Question Groups 10-13: Students are provided quantitative information about a rotating object and must calculate the angular acceleration.

Before using the Concept Builder with your classes, we recommend that teachers attempt each of the activities in order to determine which are most appropriate for your classes and what pre-requisite understanding a student must have in order to complete it. Alternatively, the questions are provided in a separate file for preview purposes. Students will need to be comfortable with variables that affect the amount of linear or angular velocity.

In order to complete an activity, a student must correctly analyze each question in 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 level (displayed for Task Tracker users). A star is an indicator of correctly analyzing the question. Once a star is earned, that question is removed from the queue 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 in an activity has been analyzed, the student earns a Trophy which is displayed on the Main Menu.

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.

We do not have a lot of resources on the topic of Rotational Motion at The Physics Classroom website. What we do have is listed below. We hope to be adding more in the future.