Unit Plan 16 (Grade 8 Science): Engineering with Forces & Motion

Focus: Evaluate design solutions involving balanced forces, collisions, and transport systems, applying Newton’s Third Law and using data to compare competing designs.

Grade Level: 8

Subject Area: Science (Physical Science • Engineering Design • Forces & Motion)

Total Unit Duration: 5 sessions (one week), 50–60 minutes per session

I. Introduction

Students apply their understanding of forces and motion to an engineering design context. They examine collisions and transport systems (like carts, bumpers, or protective carriers) through the lens of Newton’s Third Law—that for every action, there is an equal and opposite reaction between two interacting objects. Using a structured design challenge, students build and test simple prototypes (e.g., collision-safety systems for carts), then evaluate competing solutions using criteria, constraints, and test data. By the end of the unit, they can use evidence to argue which design best meets the goals and why.

Essential Questions

• How does Newton’s Third Law help us understand what happens during collisions and interactions between objects?
• How can we design and evaluate systems (like bumpers or transport devices) to manage forces and reduce damage?
• What makes one design solution better than another when we consider criteria, constraints, and data from tests?
• How can we use data from repeated tests to compare similarities and differences among solutions?
• Why is evaluating and improving designs a key part of engineering with forces and motion?

II. Objectives and Standards

Learning Objectives — Students will be able to:

1. Describe Newton’s Third Law in terms of action–reaction force pairs during collisions and interactions between objects (e.g., cart and wall, bumper and obstacle).
2. Identify design criteria and constraints for a forces-and-motion engineering challenge (e.g., protecting a fragile object while staying under a material limit).
3. Develop and/or select competing design solutions (e.g., different bumper or carrier designs) to address a problem involving balanced forces, collisions, or transport systems.
4. Plan and conduct tests of each solution, collecting data on performance (e.g., damage to payload, stopping distance, peak force indicator, or qualitative damage scale).
5. Analyze and interpret data to determine similarities and differences in how well each design meets the criteria and constraints.
6. Use a systematic process (e.g., scoring rubric, decision matrix) to evaluate competing solutions and make a justified recommendation for improvement.
7. Clearly explain how their chosen or improved design reflects Newton’s Third Law and manages forces during collisions.

Standards Alignment — 8th Grade (NGSS-based custom)

• MS-ETS1-2 — Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.
• MS-ETS1-3 — Analyze data from tests to determine similarities and differences among several design solutions and to identify the best characteristics of each that can be combined into a new solution.
• MS-PS2-1 — Apply Newton’s Third Law to design a solution to a problem involving the motion of two interacting objects.

Success Criteria — Student Language

• I can explain a collision or interaction using Newton’s Third Law, naming the action and reaction forces between two objects.
• I can identify and use criteria and constraints to compare different design solutions.
• I can collect and analyze data from tests (like number of cracks, distance, or damage rating) to see which designs work better.
• I can use a systematic process (like a scoring table or decision matrix) to decide which design best meets our goals.
• I can explain, with evidence, why one design is better and how it could be improved by combining the best features of several solutions.