### Notes:

The Case Studies: Impulse and Force 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 Interactive 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:

This Concept Builder is intended for use in the middle to later stages of a learning cycle on Impulse and Momentum Change Theorem. It forces students to apply the theorem in order to analyze two collisions in terms of mass, time, velocity change and force. Students are presented with two similar situations that differ only in terms of one of the variables - velocity change, time, and mass. Students must identify the variable that is different in the two situations. They then must determine how the variation in velocity change, time or mass affects the momentum change, impulse and force.

This exercise is not about plug-and-chug; it's about thinking and reasoning. The Concept Builder provides students with excellent practice in thinking about the variables in the impulse and momentum change theorem. They will also be challenged to read carefully (and to make sense of the reading) and to think analytically. Attention will have to be given to the before- and after-collision velocities in the two situations in order to determine if the two collisions have the same or different velocity change. With knowledge of the relative velocity change for the two situations and of the mass, they can begin to reason through the first three comparisons of Case A and Case B. The final comparison is of the relative force in the two cases. In the end, students will need to use the F•t = m•∆v equation as a guide to thinking about collisions.

This Concept Builder was intended as an in-class activity. The Concept Builder includes 16 different questions organized into 8 different Question Groups spread across two different difficulty levels. Teachers using the Concept Builder with their classes should preview the activity (or view the Questions in the separate file) in order to judge which difficulty levels would be most appropriate for their students. Our summary of the two difficulty levels is as follows:

• Master Difficulty Level: Question Groups 1 - 4
• Wizard Difficulty Level: Question Groups 1 - 8

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.

### Related Resources

There are numerous resources at The Physics Classroom website that serve as very complementary supports for the Case Studies: Impulse and Force Concept Builder. These include:

• Minds On Physics Internet Modules:
The Minds On Physics Internet Modules include a collection of interactive questioning modules that help learners assess their understanding of physics concepts and solidify those understandings by answering questions that require higher-order thinking. Assignments MC2, MC3, and MC4 from the Momentum and Collisions module make for a great complement to this Concept Builder. They are best used in the middle to later stages of the learning cycle. Visit the Minds On Physics Internet Modules.

Users may find that the App version of Minds On Physics works best on their devices. The App Version can be found at the Minds On Physics the App section of our website. The Momentum and Collisions module can be found on Part 3 of the six-part App series. Visit Minds On Physics the App.

• Curriculum/Practice: Several Concept Development worksheets at the Curriculum Corner will be very useful in assisting students in cultivating their understanding, most notably ...

Momentum, Impulse and Momentum Change
Controlling a Collision
Simple Computation with Impulse = Momentum Change

Visit the Curriculum Corner - Momentum.

Additional resources and ideas for incorporating the Case Studies: Impulse and Force 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.