Graphics
Like all our Science Reasoning Center activities, the completion of the Collisions activity requires that a student use provided information in the form of a diagram, graph, or table to answer questions. This information is accessible within the activity and is large enough to be viewable without any further action.

### The Standards

This NGSS-inspired Collisions task consists of four activities. Each activity involves a different type of skill or understanding. Collectively, these four activities were designed to address the following NGSS performance expectation:

HS-PS2-2:
Use mathematical representations to support the claim that the total momentum of a system is conserved when there is no net force on the system

As a whole, the questions in this task address a wide collection of disciplinary core idea (DCI), crosscutting concepts (CCC), and science and engineering practices (SEP). There are 56 questions organized into 16 question Groups and spread across the four activities. Each question is either a 2D or (preferrably) a 3D question. That is, the task of answering the question requires that the student utilize at least two of the three dimensions of the NGSS science standards - a DCI, a CCC, and/or an SEP.

The following DCI, SEPs, and CCCs are addressed at some point within Collisions:

DCI:  PS2.A: Forces and Motion
• Momentum is defined for a particular frame of reference; it is the mass times the velocity of the object
• If a system interacts with objects outside itself, the total momentum of the system can change; however, any such change is balanced by changes in the momentum of objects outside the system.

SEP 2.1:  Developing and Using Models
Evaluate merits and limitations of two different models of the same proposed tool, process, mechanism, or system in order to select or revise a model that best fits the evidence or design criteria.

SEP 4.1:  Analyzing and Interpreting Data

Analyze data using tools, technologies, and/or models (e.g., computational, mathematical) in order to make valid and reliable scientific claims or determine an optimal design solution.

SEP 5.3: Using Mathematical and Computational Thinking
Use mathematical representations of phenomena to describe explanations.

SEP 7.2: Engaging in Argument from Evidence
Evaluate the claims, evidence, and/or reasoning behind currently accepted explanations or solutions to determine the merits of arguments.

CCC 1.5:  Patterns
Mathematical representations are needed to identify some patterns.

CCC 3.2:  Scale, Proportion, and Quantity

Algebraic thinking is used to examine scientific data and predict the effect of a change in one variable on another (e.g., linear growth vs. exponential growth).

CCC 4.1:  Systems and System Models
When investigating or describing a system, the boundaries and initial conditions of the system need to be defined.

Here is our NGSS-based analysis of each individual activity of the Collisions Science Reasoning task. The core ideas, crosscutting concepts, and science and engineering practices that we reference in our analysis are numbered for convenience. You can cross-reference the specific notations that we have used with the listings found on the following pages:

#### Part 1: Systems

This activity consists of 16 forced-choice questions organized into four Question Groups. Students are presented a diagram of a collision with the designation of a system and four statements pertaining to forces and/or momentum. They must identify the correct statement.

NGSS Claim StatementUse mathematical representations to support the claim that the total momentum of a system is conserved when there is no net force on the system

 Target DCI(s) Target SEP(s) Target CCC(s) Forces and Motion PS2.A Momentum is defined for a particular frame of reference; it is the mass times the velocity of the object. If a system interacts with objects outside itself, the total momentum of the system can change; however, any such change is balanced by changes in the momentum of objects outside the system. Using Mathematical and Computational Thinking SEP 5.3 Use mathematical representations of phenomena to describe explanations. Systems and System Models CCC 4.1 When investigating or describing a system, the boundaries and initial conditions of the system need to be defined.

#### Part 2: Momentum in Collisions

This activity consists of 18 forced-choice questions organized into five Question Groups. Students are provided data pertaining to a collision and must use momentum conservation to identify a missing momentum value or a trial that violates the law of momentum conservation. Students must show expertise on each Question Group before being rewarded the trophy for this activity.

NGSS Claim StatementAnalyze a table of data to predict the missing information to demonstrate the momentum must be conserved in a closed system collision.

 Target DCI(s) Target SEP(s) Target CCC(s) Forces and Motion PS2.A Momentum is defined for a particular frame of reference; it is the mass times the velocity of the object. If a system interacts with objects outside itself, the total momentum of the system can change; however, any such change is balanced by changes in the momentum of objects outside the system. Analyzing and Intepreting Data SEP 4.1 Analyze data using tools, technologies, and/or models (e.g., computational, mathematical) in order to make valid and reliable scientific claims or determine an optimal design solution. Scale, Proportion, and Quantity CCC 3.2 Algebraic thinking is used to examine scientific data and predict the effect of a change in one variable on another (e.g., linear growth vs. exponential growth).

#### Part 3: Modeling Collisions

This activity consists of 20 forced-choice questions organized into five Question Groups. Students are provided mass values and a plot representing either position, velocity, or momentum values over the course of time (pre- and post-collision) and identify whether the data demonstrate (or don't demonstrate) momentum conservation and identify the reason why.

NGSS Claim StatementEvaluate the merits of two different models for a given collision/explosion in order to identify patterns that must be present.
 Target DCI(s) Target SEP(s) Target CCC(s) Forces and Motion PS2.A Momentum is defined for a particular frame of reference; it is the mass times the velocity of the object. If a system interacts with objects outside itself, the total momentum of the system can change; however, any such change is balanced by changes in the momentum of objects outside the system. Developing and Using Models SEP 5.2 Evaluate merits and limitations of two different models of the same proposed tool, process, mechanism, or system in order to select or revise a model that best fits the evidence or design criteria. Patterns CCC 3.2 Mathematical representations are needed to identify some patterns.

#### Part 4: Agree or Disagree

This activity consists of two sets of five statements - one set pertaining to explosions and the other set pertaining to a hit-and-bounce collision. Students must identify which statements they agree and disagree with. Statements are presented in a random order. Students are allowed multiple opportunities to arrive at a correct set of answers.

NGSS Claim StatementUse a model to predict the effects of a change in one variable on another for objects that travel in elliptical orbits.

 Target DCI(s) Target SEP(s) Target CCC(s) Forces and Motion PS2.A Momentum is defined for a particular frame of reference; it is the mass times the velocity of the object. If a system interacts with objects outside itself, the total momentum of the system can change; however, any such change is balanced by changes in the momentum of objects outside the system. Developing and Using Models SEP 2.1 Make a qualitative claim regarding the relationship between variables. Patterns CCC 1.5 Cause and effect relationships can be predicted for complex natural systems.

Complementary and Similar Resources
The following resources at The Physics Classroom website complement the Collisions Science Reasoning Activity. Teachers may find them useful for supporting students and/or as components of lesson plans and unit plans.

Physics Classroom Tutorial, Momentum and Its Conservation Chapter: Momentum Conservation Principle

Physics Video Tutorial, Momentum, Collisions, and Explosions: Action-Reaction and the Law of Momentum Conservation

Physics Interactives, Momentum and Collisions: Collision Carts Simulation

Physics Interactives, Momentum and Collisions: The Cart and the Brick Simulation

Physics Interactives, Momentum and Collisions: Exploding Carts Simulation

Concept Builders, Momentum and Collisions: Law Enforcement - Explosions

Concept Builders, Momentum and Collisions: Law Enforcement - Hit and Stick Collisions

Concept Builders, Momentum and Collisions: Keeping Track of Momentum - Hit and Stick Collisions

Minds On Physics, Momentum and Collisions Module, Missions MC-MC10

The Calculator Pad, Momentum and Collisions Chapter, Problem Sets MC6 - MC10