This World of Things

Given: Khushi drew a picture of her bright classroom with sunlight shining through the windows.

Answer (sample names of things typically seen in a classroom):
- Window (with glass panes)
- Door (with hinges and latch)
- Table
- Chair
- Blackboard / Chalkboard
- Light bulb
- Electric switch
- Mat / Floor

*(Note: Students should label the objects they can identify in the picture provided in their textbook.)*

Given: A classroom window with a glass pane.

Concept: Materials that allow light to pass through them completely are called transparent materials.

Answer: Yes, we can see through the window glass because glass is a transparent material. It allows light to pass through it freely, so we can clearly see objects on the other side — like trees, flowers, and the sky outside.

Instructions for students:
1. Observe your classroom carefully.
2. Draw the classroom showing objects such as: desks, chairs, blackboard, windows, doors, light bulbs, electric switches, mats, fans, etc.
3. Label each object clearly.

Sample labels to include:
- Table (made of wood)
- Chair (made of wood)
- Window (made of glass and wood/metal frame)
- Door (made of wood, with metal hinges and latch)
- Light bulb (made of glass)
- Electric switch (made of plastic)
- Mat (made of fibre/cloth)

*(This is a hands-on activity; students should draw and label based on their own classroom.)*

Given: We need to find objects made of metals in and around the classroom.

Concept: Metals are materials that are usually shiny, hard, and conduct heat and electricity. Common metals include iron, copper, aluminium, gold, silver, and alloys like steel, brass, and bronze.

Sample list of metallic objects and the metals they are made of:

| Object | Metal |
|---|---|
| Door hinges | Iron / Steel |
| Nails | Iron / Steel |
| Door latch | Iron / Steel |
| Spoon | Steel / Stainless steel |
| Coins | Copper / Nickel alloy |
| Tap / Faucet | Brass |
| Aluminium foil | Aluminium |
| Wires inside bulb | Tungsten / Copper |
| Bangles | Gold / Silver / Brass |

*(Students should add objects they observe around them.)*

Answer:
- Mats — made of fibre, coir, or cloth (natural or synthetic material)
- Light bulbs — made of glass (the outer covering) and metal (the base and filament inside)
- Electric switches — made of plastic (the outer casing) and metal (the internal contacts/wires)

So different objects in the classroom are made of different materials such as wood, metal, glass, plastic, and fibre.

Answer (sample):
- Yes, my window has a glass pane.
- Yes, I can see through it clearly because glass is transparent.
- Through the window I can see: trees, flowers, the sky, birds, other buildings, and people walking outside.

*(Students should write what they actually see through their own classroom or home window.)*

Given: We observe different materials to check how much light passes through them.

Concept:
- Transparent — allows light to pass through completely; objects can be seen clearly.
- Translucent — allows light to pass through partially; objects appear blurry.
- Opaque — does not allow light to pass through; objects cannot be seen.

Sample completed table:

| See through clearly (Transparent) | See through partially (Translucent) | Cannot see through at all (Opaque) |
|---|---|---|
| Clear glass bottle | Butter paper | Metal utensil (steel bowl) |
| Clear plastic bottle | Thin white cloth | Thick cardboard |
| Plain glass | Frosted glass | Wooden plank |
| Water in a glass | Tissue paper | Thick plastic bag |

*(Students should fill in based on their own observations.)*

Answer: One more material that is transparent is clear/plain water.

Other examples of transparent materials:
- Clear plastic (like a transparent plastic bag or bottle)
- Air

Explanation: These materials allow light to pass through them completely, so we can see objects clearly through them.

Given: Translucent materials allow light to pass through only partially — we can see through them, but not clearly.

Examples of translucent materials:
1. Butter paper (used in baking)
2. Frosted glass (used in bathroom windows)
3. Thin white cloth or muslin
4. Tissue paper
5. Wax paper
6. Some types of plastic sheets

Explanation: When you hold butter paper or frosted glass in front of a light source, you can see the light but cannot see the objects clearly behind it.

Given: We look at objects through coloured transparent materials.

Concept: When light passes through a coloured transparent material, only that colour of light passes through, making everything appear in that colour.

(a) Does the colour of the paper appear to change?
Yes! The white paper appears to take on the colour of the transparent material we are looking through. For example, through blue plastic, the white paper looks blue.

(b) Does white paper appear different through thin blue or yellow plastic/glass?
Yes:
- Through blue plastic → white paper looks blue
- Through yellow plastic → white paper looks yellow

(c) Do the colours of different objects appear to change?
Yes, the colours change. For example:
- A blue object seen through yellow plastic appears green (because blue + yellow = green in light mixing).
- A red object seen through blue plastic appears dark/purple.

(d) Earlier experiences:
Yes — for example, looking through coloured sunglasses, looking through the coloured glass of a stained-glass window, or looking through a coloured cellophane wrapper all give similar experiences.

*(Students should record their own observations from the activity.)*

Given: A table with materials and example objects.

Completed table (sample answers):

| Khushi's list | Name of the material | Objects made of this material in your classroom or home |
|---|---|---|
| Table, chair, door | Wood | Pencil, bookshelf, window frame, cricket bat, ruler |
| Door hinges, nails | Metal | Spoon, scissors, needle, coin, tap, lock |
| Windowpanes, light bulb | Glass | Mirror, spectacles, glass tumbler, bottle |
| Electric switches | Plastic | Pen, comb, bucket, water bottle, toy |
| (Additional row) | Clay | Pot, earthen lamp (diya), flower vase |

Sources of materials:
- Wood → Trees (forests)
- Metals → Earth / Mines (metals are extracted from ores found underground)
- Cloth → Plants (cotton comes from the cotton plant) and Animals (wool comes from sheep; silk from silkworms)

Answer:

- Wood → Trees (forests)
- Metals → Earth / Underground mines (metals are found as ores in the earth's crust and are extracted by mining)
- Cloth → Plants and Animals
- Cotton cloth → Cotton plant
- Woollen cloth → Sheep (wool)
- Silk cloth → Silkworm
- Jute cloth → Jute plant

Conclusion: Most materials we use come from nature — either from plants, animals, or from the earth.