Calculating speed
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👩 Teacher’s Guide
🎯 Objective
Students will be able to:
- Use speed = distance ÷ time and rearrange it
- Convert units correctly between m/s and km/h
- Check answers for reasonableness using estimation
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📝 Teaching Notes
- Key idea to emphasize: The equation speed = distance ÷ time connects three measurable quantities.
- Common misconception: Mixing units (km with seconds, etc.).
- Suggested teaching approach:
- Do unit-conversion warmups (km/h ↔ m/s).
- Practice rearranging: distance = speed × time, time = distance ÷ speed.
- Check answers using estimation.
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💬 Discussion Starter
Ask students:
- How can two journeys have the same average speed but different motion?
- Why do units matter as much as the numbers?
- How can graphs tell a story about motion?
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🧒 Student Worksheet
Concept and Helping Material
You can calculate speed using speed = distance ÷ time. Converting units correctly (m, km, s, h) is essential for accurate answers.
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Vocabulary and Definitions
- — A rule written with symbols, such as speed = distance ÷ time.
- — Change the subject of an equation.
- — Change units without changing the physical amount.
- — Kilometres per hour, a common speed unit.
- — Make a sensible approximate calculation to check an answer.
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Hands-On Experiment or Activities
Activity 1: Unit Conversion Stations
What You Need: conversion cards, calculator.
What You Do: Convert between km/h and m/s and explain the factor used (÷3.6 or ×3.6).
Think and Talk: What changed? What stayed the same?
Activity 2: Formula Triangle Practice
What You Need: worksheet, calculator.
What You Do: Use a triangle diagram to rearrange speed, distance, and time for different questions.
Think and Talk: What changed? What stayed the same?
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Practice Questions (QA)
1. Write the speed equation.
2. Rearrange to find distance.
3. Rearrange to find time.
4. Convert 72 km/h to m/s.
5. Convert 10 m/s to km/h.
6. A car travels 150 km in 2 h. Average speed?
7. A cyclist at 6 m/s rides for 50 s. Distance?
8. A runner covers 400 m at 8 m/s. Time?
9. Why check unit consistency?
10. What is a sensible speed estimate for walking?
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Reflection
- Where do you see this idea in sports, travel, or everyday movement?
- What is one measurement or graph habit that would improve your answers?