This World of Things — NCERT Solutions

This is a discussion/interview activity. Sample answers based on common knowledge:

(a) Were things made of the same materials in their childhood?
Not always. For example:

• Buckets and containers were often made of metal (iron or brass), whereas today we mostly use plastic buckets.
• Combs were made of wood or bone, now they are mostly plastic.
• Toys were made of wood or clay, now many are made of plastic.

(b) Are there new materials now that they might not have seen before?
Yes! Plastic is a relatively new material that was not widely used in earlier times. Synthetic fibres (like nylon and polyester) for clothes are also newer materials.

(c) Are there materials from their childhood not in use now?
Yes, for example:

• Clay pots for storing water were very common but are now replaced by plastic or metal containers.
• Leaf plates (pattal) were used for eating but are now replaced by plastic or steel plates.
• These older materials are less used because newer materials are cheaper, lighter, or more durable.

(Students should record actual answers from their grandparents.)

Given: We observe and describe a spoon.

Answer (for a typical steel/metal spoon):

• Material: The spoon is made of metal (stainless steel).
• Description:
• ✅ Smooth — the surface of a metal spoon is smooth.
• ✅ Shiny — metal spoons are shiny and reflect light.
• ✅ Feels cold to the touch — metals feel cold when you first touch them because they conduct heat away from your hand quickly.
• ❌ Not rough.
• ❌ Not dull (it is shiny).

For a wooden spoon:

• Smooth or slightly rough, Dull (not shiny), does NOT feel cold to the touch.

(Students should describe the spoon they actually have at home.)

Given: We tap a metal spoon on objects of different materials and observe the sounds.

Concept: Different materials produce different sounds when struck because of their different densities and structures.

Sample observations:

Sample beat composition:
Ting, Ting, Thak, Thak
Ting, Thak, Ting, Thak!
Tak, Tak, Dub, Ting!

(Students should compose their own beats based on their observations.)

Answer:

Other materials used to make tables:

• Metal (iron or steel)
• Plastic
• Glass (glass-top tables)
• Stone or marble

Can we use fabric or rubber to make a table?
No, we cannot use fabric or rubber to make a table.

Reason:

• Fabric is soft and flexible — it cannot hold its shape or support weight. A table made of fabric would collapse.
• Rubber is also flexible and elastic — it would bend and not provide a firm, flat surface to keep things on.

Conclusion: A table needs to be made of a hard and rigid material so that it keeps its shape and can support the weight of objects placed on it. Wood, metal, and stone are hard and rigid, making them suitable for making tables.

Given: We must find unsuitable material-object pairs and explain why.

Concept: The material used to make an object must match the properties needed — hardness, flexibility, waterproofing, strength, etc.

Completed table:

Given: Objects — ink, a stone, smoke, ice, steam, a spoon, honey, a bottle, a bag, water.

Concept:

• Solid — has a fixed shape and does not flow (e.g., stone, wood).
• Liquid — has no fixed shape; it flows and takes the shape of its container (e.g., water, milk).
• Gas — has no fixed shape or volume; it spreads out in all directions (e.g., air, steam).

Grouping:

🟫 Tray (Solids):

• A stone
• Ice
• A spoon
• A bottle
• A bag

🔵 Bottle (Liquids):

• Ink
• Honey
• Water

🎈 Balloon (Gases):

• Smoke
• Steam

Confusing objects (neither clearly solid, liquid, nor gas):

1. Sand — looks like it flows (like a liquid) but each grain is actually a tiny solid.
2. Sponge — is a solid but has holes filled with air; it can absorb liquids.
3. Clay — is a solid but can be moulded and shaped like a liquid when wet.

(Students can add their own examples to the tray, bottle, and balloon.)

Given: Natural things exist in nature (not made by humans). Artificial things are made by people.

Concept:

• Natural things may be living (plants, animals) or non-living (rocks, water, air).
• Artificial things are manufactured or created by human beings.

Answer:

Natural things (5 examples):

1. Mango tree
2. River / Water
3. Rocks / Stones
4. Birds
5. Air / Wind

Artificial things (5 examples):

1. Table
2. Shoes
3. Plastic bottle
4. Electric bulb
5. Clothes / Fabric

Given: Khushi drew a mango tree with mangoes growing on it.

Answer: Khushi most likely drew her picture around June (summer season).

Reason: Mango trees bear fruit during the summer months — typically from April to July in India. Mangoes are ripe and available in the market during this time. In January, it is winter and mango trees do not bear fruit — they may not even have flowers yet.

Conclusion: Since Khushi drew a mango tree with mangoes on it, the picture was drawn around June (summer), not January.

Answer:

Three materials we commonly see around us are:

1. Wood — used to make furniture like tables, chairs, and doors.
2. Metal (e.g., iron/steel) — used to make nails, hinges, spoons, and utensils.
3. Plastic — used to make bottles, bags, switches, and pens.

(Other acceptable answers: glass, cloth/fabric, clay, rubber, stone.)

Given: A shining spoon — we need to find out if it is truly metal or just painted to look shiny.

We can test it in the following ways:

1. Feel the temperature: Hold the spoon for a moment. If it feels cold to the touch and quickly takes on the temperature of your hand, it is likely metal (metals are good conductors of heat). Non-metals like plastic or wood do not feel as cold.

2. Tap it: Gently tap the spoon on a hard surface. A metal spoon produces a clear ringing sound (ting-ting). A plastic or wooden spoon produces a dull sound.

3. Check the weight: Metal spoons are generally heavier than plastic or wooden spoons of the same size.

4. Scratch test: Gently scratch a hidden part of the spoon. If the scratch reveals a different colour underneath, it may be painted. If the colour is the same throughout, it is likely the natural material.

5. Magnet test: If you have a magnet, bring it near the spoon. If the spoon is attracted to the magnet, it is made of iron or steel (a metal).

Conclusion: By using these simple tests — feeling the temperature, tapping, checking weight, scratching, and using a magnet — we can find out whether the spoon is truly made of metal or just painted to look shiny.

Instructions for students:

Three Natural things to draw:

1. A tree (e.g., mango tree with fruits)
2. A river or a pond with water
3. A bird (e.g., sparrow or parrot)

Three Artificial things to draw:

1. A table and chair
2. A plastic bottle
3. An electric bulb

Remember:

• Natural things are found in nature and are NOT made by humans.
• Artificial things are made by humans.

(Students should draw these in their notebooks with neat labels.)

Given: We need to match the type of material with the correct example.

Concept:

• Transparent — allows light to pass through completely; we can see clearly through it.
• Translucent — allows light to pass through partially; we can see only partially through it.
• Opaque — does not allow light to pass through; we cannot see through it.

Correct Matches:

Explanation:

• Spectacle glass is transparent — we can see clearly through it.
• A paper lamp shade is translucent — it allows some light to pass through but we cannot see objects clearly through it; it glows softly.
• A plate (made of metal, ceramic, or thick plastic) is opaque — no light passes through it.