Science Lesson Kit · Teacher Resource
Balanced & Unbalanced Forces — 5E Lesson Plan
Physical Science · 45 minutes
Grade 3
5E lesson flow
01
Engage
6 min
Teacher Does
Use the cart and two push paddles to demonstrate opposite pushes. First model equal relative pushes, then make only one push stronger.
Students Do
Observe and describe what stayed the same and what changed.
Ask
- What stayed the same?
- What changed?
Look For
Motion evidence connected to the changed force condition.
02
Explore
13 min
Teacher Does
Guide safe qualitative force comparisons.
Students Do
Predict, change one condition, observe, and record.
Ask
- Which one force condition did you change?
Look For
One-variable comparisons and recorded observations.
03
Explain
8 min
Teacher Does
Formalize force, direction, balanced forces, unbalanced forces, and evidence. State: Balanced forces do not mean no forces are acting. They mean the object's motion does not change because of those forces.
Students Do
Use force diagrams and observations to explain a trial.
Ask
- What is your evidence?
Look For
Cause-and-effect reasoning without force arithmetic.
04
Elaborate
12 min
Teacher Does
Support students as they design a one-variable comparison.
Students Do
Plan, predict, test, revise, and explain.
Ask
- How will you keep the comparison fair?
Look For
The object, surface, and starting condition stay the same.
05
Evaluate
6 min
Teacher Does
Use one at-rest case and one already-moving case.
Students Do
Explain what balanced forces mean in both cases.
Ask
- Does balanced always mean stopped?
Look For
No. Balanced means no change in motion.
Student goal
I can test how balanced and unbalanced forces affect motion and use observations as evidence.
Learning objectives
- Use observations to compare how balanced and unbalanced forces affect motion.
- Plan a fair comparison that changes one force condition at a time.
- Use observed motion as evidence for a force claim.
Materials
- Lightweight cart or box
- Flat surface
- Tape start line
- Two soft push paddles or foam blocks
- Recording sheets
- Force arrow cards
Before class
- Choose a lightweight cart or box that rolls predictably on a clear tabletop.
- Mark a start line and a safe travel zone.
- Use two soft push paddles or foam blocks so students can apply pushes without fingers near the wheels.
- Plan comparisons that change one force condition at a time.
- Keep force comparisons qualitative; do not require numerical force values.
- Open Teach Mode.
Prior knowledge
- A force is a push or pull.
- Direction tells which way a force or object points or moves.
Vocabulary
- force
- A push or pull on an object.
- motion
- A change in an object's position over time.
- balanced forces
- Forces that are equal in strength and opposite in direction, so they cause no change in an object's motion.
- unbalanced forces
- Forces that do not balance. The overall push or pull can change an object's motion.
- direction
- The way a force or object is pointing or moving.
- evidence
- Observations or measurements used to support an explanation.
Differentiation
- Use large arrow cards for direction and relative strength.
- Allow an oral explanation before writing.
- Provide the frame: The forces are ___ because ___.
- For extension, ask students to design another one-variable comparison.
Assessment
- Check fair-comparison planning.
- Review recorded motion observations.
- Use the at-rest and already-moving explanations as evidence of understanding.
Exit ticket
Draw force arrows for a cart and explain what the forces would do to its motion.
Extension
Design a new one-variable force comparison and predict the result before testing.