Changes in Materials: Useful and Harmful
Identifying Useful and Harmful Changes in Materials
Learning Standards
Content Standard
The learner demonstrates understanding of changes in materials and their effects
Performance Standard
The learner should be able to classify changes as useful or harmful and practice environmental care
Learning Competency
Classify changes in materials as useful or harmful to the environment
Code: S6MT-Ia-b-1
Complete Lesson Plan
Learning Objectives
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Identify different changes in materials
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Distinguish between physical and chemical changes
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Classify changes as useful or harmful
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Explain the effects of changes on the environment
Lesson Procedures
motivation
Show two pictures: 1) A person cooking food, 2) Smoke from burning garbage. Ask: 'Both show changes in materials. Which one is good? Which one is bad? Why?'
presentation
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Explain: 'Materials around us change all the time. Some changes help us, while others can harm us and our environment.'
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Types of Changes:
1. PHYSICAL CHANGES
- Appearance changes but it's still the same material
- Can often be reversed
- Examples:
- Ice melting to water (can freeze again)
- Cutting paper (still paper)
- Dissolving sugar in water
- Folding cloth
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2. CHEMICAL CHANGES
- New substance is formed
- Usually permanent/cannot be easily reversed
- Examples:
- Burning wood → ash and smoke
- Rusting of iron → iron oxide
- Cooking egg → solid protein
- Spoiling food → decay
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USEFUL CHANGES (Beneficial):
| Change | Why It's Useful | |--------|----------------| | Cooking food | Makes food safe to eat, easier to digest | | Making paper from trees | Creates useful products | | Recycling plastics | Reduces waste, protects environment | | Composting | Makes fertilizer for plants | | Photosynthesis | Produces oxygen we breathe | | Dissolving medicine | Helps body absorb it |
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HARMFUL CHANGES (Destructive):
| Change | Why It's Harmful | |--------|----------------| | Burning plastics | Releases toxic smoke, air pollution | | Rusting of metal | Weakens structures, wastes materials | | Spoiling food | Causes diseases, wastes resources | | Cutting trees | Destroys habitats, causes erosion | | Burning fossil fuels | Air pollution, climate change | | Mixing chemicals carelessly | Can be toxic or explosive |
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Emphasize: Same change can be useful or harmful depending on HOW it's done
- Burning: Cooking (useful) vs. Burning garbage (harmful)
- Cutting: Surgery (useful) vs. Deforestation (harmful)
generalization
Questions:
- What is the difference between useful and harmful changes?
- Can you give examples of each?
- How can we promote useful changes?
- How can we prevent or reduce harmful changes?
- What is our responsibility to the environment?
guided practice
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Classify together using T-chart:
Useful | Harmful
- Boiling water | Burning plastics
- Baking bread | Oil spills
- Recycling | Rusting
- Melting ice for drink | Spoiled food
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Discuss each example:
- Is it physical or chemical change?
- Why is it useful or harmful?
- Can we prevent the harmful ones?
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Show pictures and classify as a class
independent practice
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Activity 1: Classify each change as Useful or Harmful:
- Cooking rice - ____
- Burning old tires - ____
- Recycling cans - ____
- Rusting bicycle - ____
- Making compost - ____
- Air pollution from factories - ____
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Activity 2: Identify if Physical or Chemical change:
- Ice cream melting - ____
- Wood burning - ____
- Cutting vegetables - ____
- Milk turning sour - ____
- Water evaporating - ____
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Activity 3: Complete the table:
| Change | Useful/Harmful | Reason | |--------|---------------|--------| | Cooking fish | ? | ? | | Burning garbage | ? | ? | | Recycling paper | ? | ? |
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Activity 4: Give 3 examples each:
- Useful changes at home: ________
- Harmful changes to avoid: ________
preliminary activities
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Prayer and greetings
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Review: States of matter (solid, liquid, gas)
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Show examples of materials that have changed
Assessment
answers
- Chemical change - new substances formed, cannot be reversed
- Cooking food, recycling, composting (accept any 3 useful changes)
- Burning plastics, air pollution, rusting (accept any 3 harmful changes)
- Releases toxic smoke, pollutes air, harms health and environment
- (Accept reasonable explanations about health/environmental dangers) Bonus: (Examples: Recycle plastics instead of burning, use organic waste for compost instead of burning)
evaluation
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Answer:
- Is cooking a physical or chemical change? Why?
- Give 3 examples of useful changes in materials
- Give 3 examples of harmful changes
- Explain why burning plastics is harmful
- Situation: Your neighbor is burning old tires and plastics. What would you tell them? Why?
Bonus: Suggest one way to turn a harmful change into a useful one
Materials & Resources
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Pictures showing various changes
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Material samples (paper, ice, metal, plastic)
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Chart paper for classification
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Markers and crayons
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T-chart templates
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Environmental protection posters
assignment
Homework:
- Observe 5 changes in materials at home and classify them as useful or harmful
- Make a poster: 'Say NO to Harmful Changes' showing 3 harmful changes to avoid
- Research: What happens to plastics when burned?
Remarks:
- Emphasize environmental responsibility
- Discuss proper waste disposal and recycling in the community
subject matter
Topic: Changes in Materials - Useful and Harmful
Key Concepts:
- Physical change - change in appearance but substance stays the same (can be reversed)
- Chemical change - new substance is formed (usually permanent)
- Useful changes - beneficial to humans and environment
- Harmful changes - damage environment or health
- Examples:
- Useful: Cooking food, making paper, recycling
- Harmful: Burning plastics, air pollution, rusting
Materials:
- Pictures of different changes (burning, cooking, rusting, etc.)
- Samples: paper, ice, metal, plastic
- Chart paper
- Markers
- T-chart for classification