🎯 Learning outcomes
- Classify materials by properties: hardness, transparency, solubility, magnetic, floating, conducting heat and electricity
- Separate simple mixtures by sieving, filtering, evaporation and magnets
- Explain reducing, reusing and recycling materials
Before you start: Naming materials.
📖 Explanation
Materials differ in properties. Transparent materials (clear glass) let light through, translucent ones (butter paper) let some through, and opaque ones (wood) let none. Some substances dissolve in water (salt, sugar) and some do not (sand, oil). Iron and steel are attracted by magnets. Metals conduct heat and electricity; wood and plastic do not.
Mixtures can be separated: sieving separates flour from bran, filtering separates sand from water, evaporation gets salt from salty water, a magnet picks iron filings from sand, and winnowing separates husk from grain.
To protect the environment: reduce what we use, reuse things (glass jars, cloth bags) and recycle paper, glass and metals.
Salt is made in salt pans in Gujarat and Tamil Nadu by letting seawater evaporate in the sun.
✗ When sugar dissolves in water it disappears
✓ The sugar is still there; the water tastes sweet and you can get sugar back by evaporating the water.
🧪 Try this activity
Mix sand, salt and iron filings. Plan and carry out steps to separate all three (magnet, add water and filter, evaporate).
✍️ Question bank with answers
Tap an option to check multiple-choice answers. Open “Answer” or “Marking points” for the others.
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Which can be separated from water by filtering?
Answer
C. sand
Sand does not dissolve and stays on the filter paper.
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Which is attracted by a magnet?
Answer
D. iron nail
Iron is a magnetic material.
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Butter paper is
Answer
A. translucent
It lets some light through.
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Name a material that conducts electricity.
Answer
copper, iron or any metal
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How is salt obtained from seawater?
Answer
by evaporation
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Why are cooking pans made of metal but their handles of plastic or wood?
Marking points
- Metal conducts heat to cook food
- Plastic or wood do not conduct heat, so handles stay cool
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Explain how to get clean salt from a mixture of salt and sand.
Marking points
- Add water and stir so salt dissolves
- Filter to remove sand
- Evaporate the water to get salt crystals
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How can your family reduce plastic waste? Give three ways.
Answer
- Carry cloth bags
- Use steel bottles and boxes
- Refuse straws and single-use plates
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Draw a filtering set-up with funnel, filter paper and beaker.
Answer
- Funnel with folded filter paper
- Muddy water poured in
- Clear water collected below
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