Science Lesson Kit · Teacher Resource
Forces & Newton's Third Law — 5E Lesson Plan
Physical Science · 55 minutes
Grade 6
5E lesson flow
01
Engage
7 min
Teacher Does
Show two carts contacting.
Students Do
Predict forces on both carts.
Ask
- Who pushes whom?
Look For
Both objects exert forces.
02
Explore
13 min
Teacher Does
Provide force-pair cards and safe cart trials.
Students Do
Match equal/opposite arrows to interacting objects.
Ask
- Where does each force act?
Look For
Different objects.
03
Explain
10 min
Teacher Does
Formalize Newton's Third Law.
Students Do
Annotate diagrams with magnitude and direction.
Ask
- What stays equal? What is opposite?
Look For
Strength equal, direction opposite.
04
Elaborate
15 min
Teacher Does
Set a bumper design challenge with criteria and constraints.
Students Do
Design, test, and compare a solution.
Ask
- What evidence shows improvement?
Look For
Evidence plus requirements.
05
Evaluate
10 min
Teacher Does
Give a new collision scenario.
Students Do
Draw the pair and justify a design choice.
Ask
- How does the law inform the solution?
Look For
Correct force pair and application.
Student goal
I can model a Third-Law force pair and apply it to a collision design.
Learning objectives
- Construct a 6 N equal-and-opposite force pair on two colliding carts.
- Use criteria, constraints, and test data to compare three bumper designs.
- Recommend the only design that meets both requirements and state the one-dimensional model limit.
Materials
- Low-friction carts
- Foam/cardboard bumper materials
- Mass limit cards
- Force-pair diagrams
Before class
- Use low-speed one-dimensional cart collisions.
- Set criteria and material/mass constraints.
- Open Teach Mode.
Prior knowledge
- Students can identify pushes and pulls.
- Students can interpret force arrows.
Vocabulary
- force
- A push or pull caused by an interaction.
- interaction
- A situation in which objects affect one another.
- force pair
- Two forces that interacting objects exert on each other.
- Newton's Third Law
- Interacting objects exert forces on each other that are equal in strength and opposite in direction.
- collision
- An interaction in which objects strike one another.
- criterion
- A requirement a successful design should meet.
- constraint
- A limit on a design, such as material, time, mass, or cost.
Differentiation
- Color-code the two objects and their force arrows.
- Provide sentence frames for equal/opposite reasoning.
- Extension: compare design tradeoffs while keeping collision direction one-dimensional.
Assessment
- Check that paired forces act on different objects.
- Check equal magnitude and opposite direction.
- Check design reasoning against criteria and constraints.
Exit ticket
Draw a 5 N Third-Law pair and state which object each force acts on.
Extension
Revise the bumper after one test and justify the change with evidence.