# How Things Work

## Overview

This chapter helps students explore how different objects around them work. It focuses on real-life observation and experimentation with spinning, floating, and sinking. Through fun activities using common items like coins, spinners, boats, and aluminium foil, students learn how shape, size, weight, and material affect how things behave.

## Key Topics Covered

### 1. Observing Spinning Objects

- **Everyday Curiosity**: Students are encouraged to observe and question how common things like pencils, coins, and erasers behave when spun.
- **Activity**: Children spin different objects (coin, bangle, pencil, stone, eraser, wooden top) and record their observations and questions in a table format.
- **Key Idea**: Not all things spin well; some start shaking as they slow down. This builds critical thinking and curiosity.

### 2. Making and Testing Spinners

- **Materials Used**: Cardboard, toothpicks, pen tubes.
- **Exploration**: Students build various spinners by altering the shape (square, circle), position of holes (centered, off-center), and materials.
- **Findings**:

- Central hole spinners spin better and remain upright.
- Square cards may appear circular when spinning.
- Colour patterns blend when spun rapidly.

- **Cultural Connection**: Spinning tools like the charkha and traditional Indian tops like “lattu” are introduced.

### 3. Exploring Floating and Sinking

- **Scenario**: After rain, students play with paper boats and notice some float while others sink or flip.
- **Activity**: Drop items like leaves, nails, bowls, bottles into water to predict and observe floating/sinking.
- **Findings**:

- Heaviness alone doesn’t decide floating.
- Shape and material also matter (e.g., foil in a cup shape floats, but a ball sinks).

### 4. Making Boats

- **Creative Task**: Using everyday items (ice-cream sticks, cardboard, clay, walnut shells), students build boats in groups.
- **Assessment**: They compare boats based on strength and balance.
- **Observation**: Shape, material, and structure affect whether a boat floats or tips over.

### 5. Think and Investigate

- **Concept Questions**:

- Why do spinners stop spinning?
- What causes imbalance in a figure?
- How to make floating things sink or vice versa?

- **Sorting Task**: Classify various objects like cork, coin, candle, marble, etc., into “float” or “sink” categories.

## New Terms and Definitions

| Term | Definition |
| ----------- | ------------------------------------------------------------------------- |
| spinner | A small toy or object that spins around a central point |
| charkha | A spinning wheel used to make thread from cotton |
| float | To stay on the surface of water without sinking |
| sink | To go below the surface of water |
| balance | A state where weight is evenly spread to keep something upright or steady |
| prediction | A guess about what will happen |
| observation | What you see happening during an experiment |
| foil | A thin sheet of metal, like aluminium |
| lattu | A traditional Indian spinning top, usually made of wood |
| recyclable | Something that can be reused or processed to make new products |

Here are the **10 practice questions** based on the chapter **“How Things Work”**, divided by difficulty level with answers and explanations.

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## 📝 Practice Questions

### 🟢 Easy (3 Questions)

1. **Which of these objects is most likely to spin well?**
a) Eraser
b) Coin
c) Leaf
d) Paper clip
**Answer**: **b) Coin**
**Explanation**: Coins have a round, flat shape which makes them spin easily.

2. **What happens when a spinner slows down?**
a) It flies away
b) It shakes and stops
c) It changes colour
d) It melts
**Answer**: **b) It shakes and stops**
**Explanation**: As spinning slows, balance is lost, causing shaking before it stops.

3. **Which object will usually float in water?**
a) Stone
b) Iron nail
c) Leaf
d) Marble
**Answer**: **c) Leaf**
**Explanation**: Leaves are light and wide, so they stay on water’s surface.

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### 🟡 Medium (2 Questions)

4. **Which of the following helps a boat float better?**
a) Making it heavy
b) Giving it a cup-like shape
c) Pressing it flat
d) Using metal only
**Answer**: **b) Giving it a cup-like shape**
**Explanation**: A cup shape traps air and spreads weight, helping the boat float.

5. **Why did the spinner with the hole at the center spin better than the one with an off-center hole?**
a) It was lighter
b) It was colourful
c) It had better balance
d) It was circular
**Answer**: **c) It had better balance**
**Explanation**: A centered hole helps the spinner balance and spin properly.

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### 🔴 Difficult (3 Questions)

6. **Which of the following statements is correct?**
a) All light objects float
b) All heavy objects sink
c) Shape and air inside can also affect floating
d) Only metal objects can float
**Answer**: **c) Shape and air inside can also affect floating**
**Explanation**: Floating depends on shape, weight, and trapped air—not just weight.

7. **If an aluminium foil ball sinks, what shape might make it float?**
a) Pressed tighter
b) A cup-like shape
c) A triangle
d) No change needed
**Answer**: **b) A cup-like shape**
**Explanation**: A cup-like shape helps spread weight and trap air, making it float.

8. **A square spinner appears circular when spun. Why does this happen?**
a) The spinner shrinks
b) Our eyes blur fast motion
c) It becomes a circle
d) It spins too slowly
**Answer**: **b) Our eyes blur fast motion**
**Explanation**: Our eyes can’t track the fast edges clearly, so it appears circular.

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### 🔵 Very Difficult (2 Questions)

9. **Ravi spins a spinner. It always leans to side ‘A’. What should he do to fix it?**
a) Add more weight to side A
b) Colour side B
c) Add weight to side B
d) Remove the spinner
**Answer**: **c) Add weight to side B**
**Explanation**: To balance the spinner, equal weight must be added to the opposite side.

10. **How can you make a heavy object float in water?**
a) Throw it hard into water
b) Use rubber around it
c) Change its shape to spread weight
d) Keep it in a box
**Answer**: **c) Change its shape to spread weight**
**Explanation**: A boat shape or flat surface helps distribute weight and trap air, making floating possible even for heavy objects.

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