Activities on Composing and Decomposing Numbers in Grade 1

Master composing and decomposing numbers: place value, tens and ones, number bonds activities designed for young learners.

Concepts and Definitions
🔢 Composing & Decomposing 🔢
10
Tens
1
Ones
15
1T + 5O
Key Definitions:

Composing: Putting numbers together to make a larger number

Decomposing: Breaking apart a number into smaller parts

Place Value: Where a digit sits tells its value (tens, ones)

Base Ten: Our number system uses groups of 10

Number Bonds: Different ways to make the same number

Grade 1 Level: Working with numbers up to 100

Number = Tens + Ones
Place Value Formula
Grade 1 Strategy:
  1. Look at the number: Identify what to compose/decompose
  2. Find tens: Count groups of 10 that fit
  3. Find ones: Count remaining units
  4. Check work: Add parts to verify
Tip 1: Count by tens first (10, 20, 30...)
Tip 2: Use your fingers to group by 10!
Tip 3: Draw circles in groups of 10.
Important: Every number can be broken into tens and ones.
Remember: 10 ones = 1 ten.
Activities: Level 1-3
1 Basic Composing
Activity 1: Basic Composing
Build numbers using tens and ones. If you have 2 tens and 3 ones, what number do you make?
Activity Goal:

Composing: Building numbers from their place value parts

How to Complete:
  1. Count the tens (2 tens = 20)
  2. Count the ones (3 ones = 3)
  3. Add them together (20 + 3 = 23)
  4. Write the answer (23)
10
10
1
1
1
Tens
2
Ones
3
Number
23
Step 1: Count the tens

2 tens = 2 × 10 = 20

Step 2: Count the ones

3 ones = 3 × 1 = 3

Step 3: Add them together

20 + 3 = 23

Step 4: Check your work

Does 2 tens + 3 ones = 23? Yes!

2 tens + 3 ones = 23
Activity Result:

2 tens and 3 ones make the number 23

Grade 1 Rules:

• Place value: Tens and ones positions matter

• Counting: Group by tens first

• Verification: Check your answer makes sense

2 Basic Decomposing
Activity 2: Basic Decomposing
Break apart numbers into tens and ones. How many tens and ones are in 37?
Activity Goal:

Decomposing: Breaking numbers into their place value parts

10
10
10
1
1
1
1
1
1
1
Number
37
Tens
3
Ones
7
Step 1: Look at the number

We have the number 37

Step 2: Count the tens

How many tens are in 37? 3 tens (30)

Step 3: Count the ones

After taking away 30, we have 7 left

Step 4: Write the decomposition

37 = 30 + 7 = 3 tens + 7 ones

37 = 3 tens + 7 ones
Activity Result:

37 has 3 tens and 7 ones

Grade 1 Rules:

• Subtraction: Take away groups of 10 first

• Place value: Tens and ones positions

• Verification: Check 30 + 7 = 37

3 Number Bonds
Activity 3: Number Bonds
Show different ways to make 15. Find at least 3 different number bonds for 15.
Activity Goal:

Number Bonds: Showing different ways to compose the same number

Bond 1
10+5
Bond 2
9+6
Bond 3
8+7
Step 1: Start with place value

15 = 10 + 5 (1 ten + 5 ones)

Step 2: Find other combinations

15 = 9 + 6, 8 + 7, 12 + 3, etc.

Step 3: Check each combination

9 + 6 = 15, 8 + 7 = 15 ✓

Step 4: Practice more

Try to find as many as possible!

15 = 10+5, 9+6, 8+7, 12+3...
Activity Result:

Multiple ways to make 15 using addition

Grade 1 Rules:

• Flexibility: Numbers can be made multiple ways

• Addition: Combine parts to make whole

• Verification: Check each combination equals target

Activities: Level 4-5
4 Mixed Practice
Activity 4: Mixed Practice
Complete these problems:
42 = ___ tens + ___ ones
3 tens + 8 ones = ___
56 = ___ tens + ___ ones
Activity Goal:

Mixed Practice: Alternating between composing and decomposing

Problem 1: 42 = ___ tens + ___ ones

42 has 4 tens (40) and 2 ones (2)

Problem 2: 3 tens + 8 ones = ___

3 tens = 30, 8 ones = 8, so 30 + 8 = 38

Problem 3: 56 = ___ tens + ___ ones

56 has 5 tens (50) and 6 ones (6)

42
4T+2O
3T+8O
38
56
5T+6O
Step 1: Solve first problem

42 = 4 tens + 2 ones

Step 2: Solve second problem

3 tens + 8 ones = 38

Step 3: Solve third problem

56 = 5 tens + 6 ones

Step 4: Verify all answers

40+2=42, 30+8=38, 50+6=56 ✓

42=4T+2O, 3T+8O=38, 56=5T+6O
Activity Results:

42=4T+2O, 3T+8O=38, 56=5T+6O

Grade 1 Rules:

• Alternating: Switch between composing and decomposing

• Verification: Check each answer

• Consistency: Apply same methods to all problems

5 Challenge Activity
Activity 5: Challenge Activity
Word problems:
Emma has 2 tens and 5 ones. How many does she have total?
Tom has 43 marbles. How many tens and ones does he have?
What number has 6 tens and 9 ones?
Activity Goal:

Application: Using composing and decomposing in real contexts

Emma's Problem: 2 tens + 5 ones = ?

2 tens = 20, 5 ones = 5, so 20 + 5 = 25

Tom's Problem: 43 = ? tens + ? ones

43 has 4 tens (40) and 3 ones (3)

Third Problem: 6 tens + 9 ones = ?

6 tens = 60, 9 ones = 9, so 60 + 9 = 69

Emma
25
Tom
4T+3O
Third
69
Step 1: Solve Emma's problem

2 tens + 5 ones = 25 total

Step 2: Solve Tom's problem

43 = 4 tens + 3 ones

Step 3: Solve third problem

6 tens + 9 ones = 69

Step 4: Check all solutions

All answers verified and correct!

Emma: 25, Tom: 4T+3O, Third: 69
Challenge Results:

Emma has 25, Tom has 4 tens + 3 ones, answer is 69

Grade 1 Rules:

• Word problems: Identify key information

• Application: Use place value in real contexts

• Verification: Check solutions make sense

Composing and Decomposing Numbers Grade 1: Complete Guide

What Are Composing and Decomposing?

Composing means putting numbers together to make a bigger number. Example: 10 + 4 = 14

Decomposing means breaking apart a number into smaller pieces. Example: 14 = 10 + 4

Grade 1 Level Expectations

By the end of grade 1, students should be able to:

  • Compose and decompose numbers up to 100
  • Understand place value (tens and ones)
  • Work with numbers in various forms
  • Apply concepts to word problems
  • Show flexibility in number representation

Developmental Progression

Level 1: Teen numbers (11-19) - clear tens + ones
Level 2: Numbers 20-39 - building confidence
Level 3: Numbers 40-69 - increasing complexity
Level 4: Numbers 70-99 - advanced practice
Level 5: Mixed problems and word problems

Grade 1 Teaching Strategies

Concrete Manipulatives: Use base ten blocks, counters, or other objects

Visual Representations: Draw tens and ones, use place value charts

Verbal Reinforcement: Say "___ tens and ___ ones" aloud

Gradual Release: Start with guided practice, move to independent

Common Grade 1 Challenges

  • Mixing up tens and ones positions
  • Difficulty with zero in ones place
  • Struggling with larger numbers
  • Transitioning from concrete to abstract

Support Strategies

  • Use consistent visual aids
  • Provide frequent practice
  • Connect to real-world examples
  • Encourage multiple representations

Key Learning Objectives

  • Recognize that two-digit numbers are composed of tens and ones
  • Fluently decompose numbers into tens and ones
  • Compose numbers from given tens and ones
  • Understand the relationship between tens and ones
  • Apply concepts to solve word problems
  • Build foundation for future math concepts

Assessment Indicators

  • Accurately identifies tens and ones in numbers
  • Composes numbers from given parts
  • Decomposes numbers correctly
  • Applies concepts to word problems
  • Demonstrates understanding through explanation
  • Shows flexibility in number representation

Questions & Answers

Question: Why do we need to learn about tens and ones? Can't I just count regular numbers?

Answer: Great question! Learning about tens and ones helps your brain understand how numbers work, just like learning the alphabet helps you read words!

  • It makes adding and subtracting much easier: 23 + 15 becomes (20 + 10) + (3 + 5) = 38
  • It helps you understand bigger numbers later
  • It makes mental math faster and more accurate
  • It's the foundation for all future math

Think of it like organizing your toys - it's easier to count and find what you need when things are grouped together!

Question: My child is struggling with the concept of tens and ones. How can I help at home?

Answer: Here are effective home strategies:

  • Use everyday objects: bundle 10 straws together, group 10 coins
  • Practice with real numbers: count items in groups of 10
  • Play games: number card matching, place value bingo
  • Use visual aids: draw tens and ones, use base ten blocks
  • Be patient and encourage: celebrate small successes

The key is making it hands-on and fun! Regular practice with concrete materials helps build understanding.

Question: What are some effective activities for reinforcing composing and decomposing skills?

Answer: Here are proven activities:

  • Base ten block buildings: Construct numbers with physical blocks
  • Number bond flowers: Petals add up to center number
  • Place value mats: Organize tens and ones systematically
  • Counting collections: Group items by tens
  • Interactive games: Digital or physical matching games

Variety helps maintain engagement while reinforcing the core concepts!