You will learn
- Define balanced and unbalanced.
- Draw force diagrams.
- Predict motion.
- Explain resultant force simply.
Version 0.2 · expanded edition · built from cited public sources Content is based on the official frameworks and sources listed under Sources and standards. No official endorsement is claimed. Written in the style of common primary school assessments. No exam result is promised.
Student lesson
- Balanced forces do not change motion.
- Unbalanced forces change speed or direction.
- The bigger force wins.
- Floating needs balanced forces.
Words to know
forces that are equal and opposite
forces that are not equal
the single force that replaces all forces
a state with balanced forces
1. Discover: The floating boat
A boat floats still on a calm pond. Gravity pulls it down and the water pushes up with equal force. “The forces are balanced,” says Papa Yaw. A strong push from a pole makes it move: now the forces are unbalanced.
Think: Which way does an unbalanced force push?
2. Understand: Force balance
Idea 1: Balanced
Balanced forces are equal and opposite. A book on a table has gravity down and the table pushing up. Nothing changes.
Idea 2: Unbalanced
Unbalanced forces have a resultant force in one direction. It makes an object start, stop, speed up, slow down or turn.
Idea 3: Diagrams
Draw arrows from the object. Equal arrows in opposite directions show balance. Different lengths show a net force toward the longer arrow.
3. Worked examples
Example 1 (I show you): Predict
Book on a table.
- Balanced.
- No change.
- At rest.
Answer: Stays still.
Example 2 (We do it together): Predict
Winning team.
- Unbalanced.
- Bigger pull.
- Moves.
Answer: Rope moves toward winners.
Example 3 (You try): Draw
Moving cart.
Show the steps and answer
- Push arrow.
- Friction arrow.
- Compare.
Answer: Longer push arrow speeds it up.
Did you know?
A skydiver reaches terminal velocity when air resistance balances gravity at about 200 kilometres per hour.
Why this matters
Understanding force balance helps us build vehicles, buildings and bridges.
4. Explore: Force balance
Use a toy car and spring balance to push with different forces and draw force diagrams for each situation.
- Set the car on a table.
- Pull with a small force.
- Pull with a larger force.
- Draw diagrams.
Think about it: what did you notice?
What did you notice? Greater forces made the car speed up more.
5. Practise
Say it in a sentence
Use these starters when you talk about the lesson. Say them out loud.
- ___ forces are equal and opposite.
- ___ forces change motion.
- The ___ force is the single net force.
- An ___ has balanced forces.
Guided practice
Question 1. What are balanced forces?
Equal and opposite.
Question 2. What are unbalanced?
Not equal.
Question 3. What is resultant?
Net force.
Independent practice
Level 1: Start
- What are balanced forces?
- What are unbalanced?
- What is resultant?
- What is equilibrium?
- What changes motion?
Level 2: Grow
- Why book still?
- Why rope moves?
- Why diagrams?
Level 3: Stretch
- Draw three.
- Run the test.
- Explain.
Answers are in the answer key below. Try first, then check.
6. Apply: Science in everyday life
Explain why a floating boat stays still.
Show a sample answer
Use balanced forces.
Another one. Tell a family member one thing from this lesson. Use the words you learned.
Show a sample answer
A clear sentence that uses at least one word from Words to know.
7. Common mistakes
Fix: Balanced forces keep motion.
Fix: Forces are equal.
8. Lesson summary and revision card
- I can define balanced and unbalanced.
- I can draw force diagrams.
- I can predict motion.
- I can explain resultant force simply.
9. Check and master
Answer all 14 questions. You will see feedback after each one.
Your result appears here after you answer every question.
10. Key takeaways
- Balanced forces do not change motion.
- Unbalanced forces change speed or direction.
- The bigger force wins.
- Floating needs balanced forces.
11. Next lesson
Next lesson: Forces acting on structures. Keep going with the next idea in this course.
Exam practice
These questions are written in the style of common school and international primary assessments. Try them on your own, without looking back. Then check your answers in the marking guide. The marks are shown in brackets.
- Define balanced and unbalanced forces. [2 marks]
- Draw two force diagrams. [4 marks]
- Explain a boat afloat. [2 marks]
- Safety rule. [2 marks]
Total: 10 marks.
Marking guide and model answers
- 1 each
- Arrows [1] each; labels [1] each
- Gravity down [1]; water up [1]
- Any [1]; reason [1]
Score guide: 9 to 10 = secure. 6 to 8 = nearly there, revise the parts you missed. Under 6 = work through the lesson again with a grown-up.
Printable worksheet
- What are balanced forces?
- What are unbalanced?
- What is resultant?
- What is equilibrium?
- What changes motion?
- Why book still?
- Why rope moves?
- Why diagrams?
- Draw three.
- Run the test.
Homework
Describe the forces on a book on a table.
Answer key and marking scheme
| Question | Expected response | Marks |
|---|---|---|
| 1. What are balanced forces? | Equal and opposite. | 1 |
| 2. What are unbalanced? | Not equal. | 1 |
| 3. What is resultant? | Net force. | 1 |
| 4. What is equilibrium? | Balance. | 1 |
| 5. What changes motion? | Unbalanced. | 1 |
| 6. Why book still? | Balanced. | 1 |
| 7. Why rope moves? | Unbalanced. | 1 |
| 8. Why diagrams? | Show net force. | 1 |
| 9. Draw three. | Diagrams. | 1 |
| 10. Run the test. | Table. | 1 |
| Total | 10 |
Independent practice answers. Level 1: 1 Equal and opposite.; 2 Not equal.; 3 Net force.; 4 Balance.; 5 Unbalanced.. Level 2: 1 Balanced.; 2 Unbalanced.; 3 Show net force.. Level 3: 1 Diagrams.; 2 Table.; 3 Sentence..
Quiz answers: 1 B, 2 C, 3 A, 4 B, 5 C, 6 A, 7 B, 8 C, 9 A, 10 B, 11 C, 12 A, Challenge 1 B, Challenge 2 C.
Mastery and remediation
| Objective | Bronze (Developing) | Silver (Proficient) | Gold (Advanced) |
|---|---|---|---|
| O1 Define balanced and unbalanced | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O2 Draw force diagrams | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O3 Predict motion | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O4 Explain resultant force simply | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
Courseversity badge thresholds (overall quiz score): Gold = 90–100%; Silver = 80–89.9%; Bronze = 70–79.9%. A badge is never a full record of progress.
If a learner struggles
- Find the misconception: “Motion needs a force.” Balanced forces keep motion.
- Explain another way: use real objects, pictures or actions first, then words.
- Show a simpler example: Explain balanced forces.
- Guided practice: work through one example together and let the learner try the next one.
- Reassess: use the quiz again or the worksheet.
- Move on when the learner shows Silver-level evidence independently.
For parents and guardians
In this lesson your child studies balanced forces. You do not need to be an expert to help.
- Watch a tug of war.
- Ask “Are forces balanced?”
- Safe play.
- Ask “how do you know?” after each answer, and listen.
- Praise effort, not only right answers. Mistakes are how we learn.
- Ten to fifteen minutes a day is better than one long session.
Teacher package
1–5. Objectives, prerequisites, materials, preparation, duration
Lesson objectives. Learners will: define balanced and unbalanced; draw force diagrams; predict motion; explain resultant force simply.
Prerequisite knowledge. Grade 4 ideas: pushes and pulls, gravity, friction, simple machines and strength and stability of structures.
Materials. Toy car, balance. Low-resource options: use chalk or charcoal on a board or wall, drawings in the sand, and objects from the classroom instead of printed materials.
Preparation. Set up tables.
Suggested duration. 45–60 minutes. It can be split into two shorter sessions.
6–9. Teaching procedure, explanation notes, guided and independent activities
Introduction (5 min). Pull a rope with a partner equally and ask, “Why no movement?”
Explanation (10 min). Teach force balance.
Guided activity (10 min). Learners test.
Independent activity (10 min). Learners draw.
Assessment and reflection (5 min). Ask each learner to say one thing they learned and how they know it.
Key questions. Equal or not? Which wins?
Teacher explanation notes. Start with real objects and safe, hands-on observation. Then talk about what was seen, then draw and write. Always say “how do you know?”. Keep to the safety notes, and use local, safe materials.
10–12. Differentiation, formative assessment, common misconceptions
Support. Use real objects and pictures, short sentences and a partner. Let learners point, show or draw instead of writing. Extension. Ask learners to find a new example at home and explain how they know.
Formative assessment. Listen to learners read and explain, ask “how do you know?”, and check the independent work.
Misconceptions. “Motion needs a force.” Balanced forces keep motion.
13–15. Assessment questions, answer keys, marking scheme
Use the quiz, the 10-mark exam practice and the worksheet on this page. All answers and marking guides are in the answer sections above. Re-check every answer before use.
16–19. Remediation, enrichment, homework, teacher reflection
Remediation. Explain balanced forces. Enrichment. Look for one new example near your home or school, draw it and explain it to someone. Homework. See above.
Teacher reflection. After teaching, record: which ideas learners understood; which misconceptions occurred; which activities worked; which learners need more practice; and what to improve next time.
Sources and standards
This lesson is based on the sources below, and no official endorsement is claimed. Reference starting points: Next Generation Science Standards, Cambridge Primary Science and the IB Primary Years Programme. Where a standard code is named, it points to the official framework.
Research used to shape this lesson. Courseversity Science curriculum, Grade 5 Unit 6, topic 5; Next Generation Science Standards, forces and interactions; Cambridge Primary Science Stage 5, physics: forces and motion; IB Primary Years Programme, how the world works. These sources informed the lesson.