Notes

This Concept Builder is intended for use in the early to middle stages of a learning cycle on Impulse and Momentum Change Theorem. It forces students to quantitatively apply the theorem in order to relate impulse, force, and time information to the before- and after-collision momentum of an object. Students are presented with a before- and after-collision diagram with either momentum values or mass and velocity values given for each state. They are also presented with five collision parameters. They must identify the collision parameters that would lead to the indicated momentum change.

This Concept Builder was intended as an in-class activity. The exercise gets students thinking quantitatively about momentum and the factors that cause its change the factors that are equal to its change. Students will need to understand and use the F•t = m•∆v equation in order to be successful with this exercise. There are a total of 18 Question Groups in this exercise with each Group having three nearly identical questions. These 18 Question Groups and 54 questions are spread across three difficulty levels. Not every difficulty level is appropriate for every classroom. We recommend that teachers preview the Concept Builder before assigning it to students in order to insure that the assigned difficulty levels are appropriate for their students. The Questions can be viewed in a separate file if desired. The difficulty levels can be differentiated as follows:

• Apprentice: Question Groups 1-6. Pre- and Post-collision information includes momentum values. Answer options are of the same type for each question.
• Master: Question Groups 7-12. Pre- and Post-collision information includes mass and velocity values. Answer options vary in type for each question.
• Wizard: Question Groups13-18. Pre- and Post-collision information includes mass and velocity values. Half of the Question Groups include a change in direction. Answer options vary in type for each question. Must pick two different collision parameters.

In order to complete an activity, a student must correctly analyze each situation at that level. If a student's answer is incorrect, then the student will have to correctly answer the same or very similar question twice in order to successfully complete the difficulty level. This approach provides the student extra practice on situations for which they exhibited difficulty. As a student progresses through a difficulty level, a system of stars and other indicators are used to indicate progress on the level. A star is an indicator of correctly analyzing the situation. Once a star is earned, that situation is removed from the cue of situations 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 situation and will have to correctly analyze it twice before earning a star. A yellow box is an indicator that the situation must be correctly analyzed one time in order to earn a star. Once every situation for an activity has been successfully analyzed, the student earns a Trophy that 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-building tool 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 Concept Builder 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.

There are numerous resources at The Physics Classroom website that serve as very complementary supports for the Being Impulsive About Momentum Change Concept Builder. These include:
 

Additional resources and ideas for incorporating the Being Impulsive About Momentum Change Concept Builder into an instructional unit on Momentum and Collisions can be found at the Teacher Toolkits section of The Physics Classroom website. Visit Teacher Toolkits.