# This World of Things

## Overview
In this chapter, students explore the variety of objects around them, what these objects are made of, where the materials come from, and how they are used. The chapter also introduces concepts such as transparency, material properties, and classification of materials into solids, liquids, and gases. Through observation, drawing, comparison, and reflection activities, learners develop an appreciation for the materials that make up their world.

## Key Topics Covered

### 1. Observing Our Surroundings
- Students observe their classroom and identify everyday objects.
- They question what items are made of and who made them.
- For example, tables and chairs are made of wood; hinges and latches are made of metal.

### 2. Understanding Materials
- **Metals** come from ores found in the earth.
- **Wood** is sourced from trees.
- **Glass** is made from sand.
- **Plastic** is usually man-made using chemicals like petroleum.

### 3. Transparency of Materials
Materials are classified based on how much we can see through them:
- **Transparent**: See clearly through (e.g., glass).
- **Translucent**: See partially through (e.g., coloured plastic).
- **Opaque**: Cannot see through at all (e.g., wood).

### 4. Colour and Light
- Looking through coloured translucent materials can change how we see objects.
- Example: Looking at a white paper through blue plastic may make it appear blue.

### 5. Material Properties
Students explore:
- **Texture** (smooth, rough)
- **Shininess** (dull, shiny)
- **Flexibility** (rigid, flexible)
- **Sound** (different materials make different sounds when tapped)
- **Feel** (cold, warm to touch)

### 6. Solids, Liquids and Gases
- Objects are classified as:
- **Solids**: Fixed shape (stone, spoon)
- **Liquids**: Take shape of container (water, honey)
- **Gases**: No fixed shape, float freely (air, steam)
- A game to sort items like ink, stone, ice, etc., into these categories is included.

### 7. Natural vs Artificial Materials
- **Natural**: Found in nature (tree, water, bird).
- **Artificial**: Made by humans (chair, shoes, glass).

### 8. Odd Material Pairs
Students think critically about which materials are suitable for what use.
Example: Clothes cannot be made of wood because wood is rigid.

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## New Terms and Definitions

| Term | Definition |
|--------------|----------------------------------------------------------------------------|
| Transparent | Material you can see clearly through (like glass). |
| Translucent | Material you can see partly through (like coloured plastic). |
| Opaque | Material you cannot see through at all (like wood). |
| Flexible | Can bend easily without breaking. |
| Rigid | Hard and does not bend. |
| Solid | Keeps its own shape (e.g., spoon, rock). |
| Liquid | Flows and takes the shape of its container (e.g., water, oil). |
| Gas | Spreads out and does not have a fixed shape (e.g., air, steam). |
| Natural | Found in nature, not made by people (e.g., mango, tree, bird). |
| Artificial | Made by people (e.g., plastic toys, tables, buildings). |

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## Practice Questions

### Easy (3)
1. **What is glass made of?**
→ Sand.

2. **Which material is transparent?**
→ Glass.

3. **Give one example of a natural thing.**
→ Mango.

### Medium (2)
4. **Why is wood used to make tables and not clothes?**
→ Because wood is hard and rigid, and cloth needs to be soft and flexible.

5. **What is the difference between natural and artificial materials?**
→ Natural materials occur in nature, artificial ones are made by people.

### Difficult (3)
6. **Explain why we cannot make walls out of water.**
→ Water is a liquid and does not hold its shape; it flows.

7. **Name one item for each: transparent, translucent, and opaque material.**
→ Transparent: window glass; Translucent: coloured plastic; Opaque: wood.

8. **What do we mean when we say a material is ‘flexible’? Give an example.**
→ It can bend without breaking. Example: rubber band.

### Very Difficult (2)
9. **How can you tell if a spoon is made of metal or just painted to look like metal?**
→ You can feel its temperature (metal feels cold), test the weight, or gently tap it to hear the sound.

10. **Write three materials and give one object made from each. Also, mention whether they are natural or artificial.**
→
- Wood – Table – Natural
- Plastic – Bottle – Artificial
- Metal – Spoon – Natural (though processed)

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