# Double Century

## Overview

In this chapter, children explore numbers from 1 to 200 using real-life objects, games, and activities. They develop understanding of numbers through bundling sticks, estimating quantities, using number lines, and composing/decomposing numbers. The concept of place value (hundreds, tens, and ones) is built step-by-step through engaging tasks.

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## Key Topics Covered

### 1. Estimation and Counting Objects
- Students estimate and count objects such as oranges, bangles, laddoos, bindis, and bananas.
- Encourages making close guesses and verifying with actual counting.

### 2. The Story of Numbers
- Explains how early humans used marks to count.
- Introduces the Indian invention of the number system with only ten digits (0–9).
- Focus on the importance of zero.

### 3. Snakes and Ladders Number Game
- Questions based on movement on a Snakes and Ladders board to understand number transitions.
- Reinforces understanding of before/after numbers and number jumps.

### 4. Talking Pot Game
- A character (Pot) responds with the next number.
- Example: “I said 42, Pot said 43.”
- Builds sequencing skills and reinforces the concept of “one more”.

### 5. What is 100?
- Introduction to the number 100 using:
- 10 bundles of 10 matchsticks
- 10 packets of 10 bindis
- Links the concept to real-life examples (e.g., 100 runs in cricket).

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### 6. Making 100
- Activities include:
- Filling number sentences like “70 and 30 make 100”.
- Using number lines to find combinations that make 100.
- Representing numbers using sticks and bundles.

### 7. Petal Puzzle for 100
- Children fill numbers in flower petals so each petal totals 100.
- Develops logical thinking and addition skills.

### 8. Estimation and Verification
- Estimate then count objects like seeds or matchsticks.
- Questions to reflect on how close their guesses were.
- Understanding quantity through hands-on estimation.

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### 9. Writing Numbers Beyond 100
- Extend knowledge from 100 up to 150 and then 200.
- Use of:
- Bundles (10s)
- Loose sticks (1s)
- Table format for learning numbers: e.g., 1 bundle of 100 + 2 tens + 3 ones = 123

### 10. Match the Number
- Activity to match numbers with their correct representation in hundreds, tens, and ones.
- Use of number lines to mark numbers like 125, 149, etc.

### 11. Number Movement Game
- Team-based game using clap, snap, and pat:
- 1 clap = 100
- 1 snap = 10
- 1 pat = 1
- Example: Clap–Snap Snap–Pat Pat Pat = 123

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### 12. Counting Beyond 150
- Continue place value learning up to 200.
- Table entries include:
- Matchstick Bundles (100s)
- 10s and 1s
- Number name and numerical form

### 13. Estimating and Counting up to 200
- Use containers filled with objects like seeds.
- Estimate how many items, then count.
- Explore how many times a container must be filled to reach 200.

### 14. Number Line Activities
- Drawing jumps of 5 and 20 on number lines.
- Identifying numbers using arrows, smileys, and other marks.

### 15. Making and Representing Numbers
- Use matchsticks or gindali to form numbers like 125, 145, etc.
- Visualize on number line.
- Complete tables showing number forms and bundles.

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## New Terms and Simple Definitions

| Term | Simple Definition |
|---------------|------------------------------------------------------------------------|
| Estimate | To make a good guess about a number |
| Bundle | A group of 10 sticks tied together to help count |
| Number Line | A straight line with numbers in order, used to count or show jumps |
| Matchsticks | Small sticks used to show tens and ones |
| Century | Another name for 100 |
| Gindali | A local or creative tool used for grouping/counting in tens or more |
| Place Value | Knowing the value of a digit based on its position (hundreds, tens) |
| Clap/Snap/Pat | A fun way to represent numbers by sound and action |
| Sequencing | Arranging numbers in the right order |
| Addition Sentence | A math sentence showing numbers that add up to another number |

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## Practice Time

### Easy (3)

1. **What comes after 79?**
→ 80
_Explanation_: We add one more to 79.

2. **How many tens are there in 100?**
→ 10
_Explanation_: 10 groups of 10 make 100.

3. **Show 125 using bundles and sticks.**
→ 1 bundle of 100, 2 tens, and 5 ones

### Medium (2)

4. **Write two different number pairs that make 100.**
→ 60 + 40 and 55 + 45
_Explanation_: Both pairs total 100.

5. **Estimate and then count 30 seeds. How close were you?**
_Answer will vary with actual seeds._
_Explanation_: Helps build estimation skill.

### Difficult (3)

6. **Fill in the missing numbers on a number line: 100, ___, 120, ___, 140**
→ 110, 130
_Explanation_: Jumps of 10.

7. **Clap, Snap Snap, Pat Pat Pat – What number is it?**
→ 123
_Explanation_: 100 + 20 + 3

8. **How many different ways can you make 100 using two numbers?**
→ Many: 10+90, 20+80, 33+67, etc.
_Explanation_: Understanding number pairs.

### Very Difficult (2)

9. **Show number 189 on number line and explain its parts.**
→ 1 hundred + 8 tens + 9 ones
_Explanation_: 100 + 80 + 9

10. **Using bundles and sticks, how can you show 172?**
→ 1 bundle of 100, 7 tens, 2 ones
_Explanation_: Understanding place value breakdown.

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