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Science Lesson Kit · Teacher Resource

Balanced & Unbalanced Forces — 5E Lesson Plan

Physical Science · 45 minutes

Grade 3

5E lesson flow

  1. 01

    Engage

    6 min

    Teacher Does

    Demonstrate equal opposite pushes and then change one force condition.

    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.

  2. 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.

  3. 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.

  4. 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.

  5. 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
  • Recording sheets
  • Force arrow cards

Before class

  • Choose a lightweight cart or box that moves safely.
  • Mark a start line.
  • 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 do not cause a change in an object's motion.
unbalanced forces
Forces that can cause a change in 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.