Chapter 24: Subtraction Strategies
Learn Grade 1 mathematics from very beginner explanations through worked examples, practice, reasoning, and review.
Chapter Overview
This chapter teaches Subtraction Strategies with simple language, step-by-step reasoning, and original worked examples. Math words are explained in simple Grade 1 language.
Key Technical Terms
- Taking away objects (a Grade 1 idea used in this chapter)
- Crossing out drawings (a Grade 1 idea used in this chapter)
- Counting back (a Grade 1 idea used in this chapter)
- Counting up to find a difference (a Grade 1 idea used in this chapter)
- Using a ten frame (a Grade 1 idea used in this chapter)
- Using a number line (a Grade 1 idea used in this chapter)
- Using related addition facts (a Grade 1 idea used in this chapter)
- Choosing a subtraction strategy (a Grade 1 idea used in this chapter)
- Checking subtraction (a Grade 1 idea used in this chapter)
- Subtraction-strategy review (a Grade 1 idea used in this chapter)
How to Learn This Chapter
Read or listen to the explanation, use objects or pictures when helpful, follow one step at a time, and try the example again before checking the answer.
24.1 Taking away objects
Taking away objects is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Beginner Note
Start with real objects, fingers, or a picture. Say the idea aloud, try one small example, and check it by counting or comparing again.
10 Worked Examples with Answers and Very-Beginner Explanations
Worked Example 1
Problem: What does Taking away objects mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Taking away objects is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: Taking away objects is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Worked Example 2
Problem: Show one small example of Taking away objects.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Taking away objects is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: A correct small model or drawing can show the meaning of Taking away objects.
Worked Example 3
Problem: Which tool could help with Taking away objects?
- Think about counters, fingers, a ten frame, number line, picture, table, or real object.
- Choose the tool that makes the idea easiest to see.
Very beginner explanation: Taking away objects is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: Use a simple tool that lets you see and check the quantities or shapes.
Worked Example 4
Problem: How can you check your work in Taking away objects?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Taking away objects is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: Check by recounting, comparing, or using a second simple model.
Worked Example 5
Problem: Where might you use Taking away objects in everyday life?
- Think about toys, snacks, books, classroom objects, calendars, shapes, or money.
- Choose one situation.
- Explain how the math helps.
Very beginner explanation: Taking away objects is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: Taking away objects can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: Show Taking away objects with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Taking away objects best through concrete examples and clear words.
Answer: A correct simple example of Taking away objects.
Worked Example 7
Problem: Show Taking away objects with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Taking away objects best through concrete examples and clear words.
Answer: A correct simple example of Taking away objects.
Worked Example 8
Problem: Show Taking away objects with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Taking away objects best through concrete examples and clear words.
Answer: A correct simple example of Taking away objects.
Worked Example 9
Problem: Show Taking away objects with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Taking away objects best through concrete examples and clear words.
Answer: A correct simple example of Taking away objects.
Worked Example 10
Problem: Show Taking away objects with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Taking away objects best through concrete examples and clear words.
Answer: A correct simple example of Taking away objects.
Practice Exercise
Create one small question about Taking away objects. Show it with objects, a picture, or numbers, then check by counting or comparing again.
24.2 Crossing out drawings
Crossing out drawings is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Beginner Note
Start with real objects, fingers, or a picture. Say the idea aloud, try one small example, and check it by counting or comparing again.
10 Worked Examples with Answers and Very-Beginner Explanations
Worked Example 1
Problem: What does Crossing out drawings mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Crossing out drawings is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: Crossing out drawings is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Worked Example 2
Problem: Show one small example of Crossing out drawings.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Crossing out drawings is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: A correct small model or drawing can show the meaning of Crossing out drawings.
Worked Example 3
Problem: Which tool could help with Crossing out drawings?
- Think about counters, fingers, a ten frame, number line, picture, table, or real object.
- Choose the tool that makes the idea easiest to see.
Very beginner explanation: Crossing out drawings is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: Use a simple tool that lets you see and check the quantities or shapes.
Worked Example 4
Problem: How can you check your work in Crossing out drawings?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Crossing out drawings is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: Check by recounting, comparing, or using a second simple model.
Worked Example 5
Problem: Where might you use Crossing out drawings in everyday life?
- Think about toys, snacks, books, classroom objects, calendars, shapes, or money.
- Choose one situation.
- Explain how the math helps.
Very beginner explanation: Crossing out drawings is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: Crossing out drawings can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: Show Crossing out drawings with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Crossing out drawings best through concrete examples and clear words.
Answer: A correct simple example of Crossing out drawings.
Worked Example 7
Problem: Show Crossing out drawings with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Crossing out drawings best through concrete examples and clear words.
Answer: A correct simple example of Crossing out drawings.
Worked Example 8
Problem: Show Crossing out drawings with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Crossing out drawings best through concrete examples and clear words.
Answer: A correct simple example of Crossing out drawings.
Worked Example 9
Problem: Show Crossing out drawings with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Crossing out drawings best through concrete examples and clear words.
Answer: A correct simple example of Crossing out drawings.
Worked Example 10
Problem: Show Crossing out drawings with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Crossing out drawings best through concrete examples and clear words.
Answer: A correct simple example of Crossing out drawings.
Practice Exercise
Create one small question about Crossing out drawings. Show it with objects, a picture, or numbers, then check by counting or comparing again.
24.3 Counting back
Counting back helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Beginner Note
Start with real objects, fingers, or a picture. Say the idea aloud, try one small example, and check it by counting or comparing again.
10 Worked Examples with Answers and Very-Beginner Explanations
Worked Example 1
Problem: What does Counting back mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Counting back helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Counting back helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Worked Example 2
Problem: Show one small example of Counting back.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Counting back helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: A correct small model or drawing can show the meaning of Counting back.
Worked Example 3
Problem: Which tool could help with Counting back?
- Think about counters, fingers, a ten frame, number line, picture, table, or real object.
- Choose the tool that makes the idea easiest to see.
Very beginner explanation: Counting back helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Use a simple tool that lets you see and check the quantities or shapes.
Worked Example 4
Problem: How can you check your work in Counting back?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Counting back helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Check by recounting, comparing, or using a second simple model.
Worked Example 5
Problem: Where might you use Counting back in everyday life?
- Think about toys, snacks, books, classroom objects, calendars, shapes, or money.
- Choose one situation.
- Explain how the math helps.
Very beginner explanation: Counting back helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Counting back can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: Count to 6. What number comes just before 6?
- Count forward until 6.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 5
Worked Example 7
Problem: Count to 12. What number comes just before 12?
- Count forward until 12.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 11
Worked Example 8
Problem: Count to 19. What number comes just before 19?
- Count forward until 19.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 18
Worked Example 9
Problem: Count to 27. What number comes just before 27?
- Count forward until 27.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 26
Worked Example 10
Problem: Count to 44. What number comes just before 44?
- Count forward until 44.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 43
Practice Exercise
Create one small question about Counting back. Show it with objects, a picture, or numbers, then check by counting or comparing again.
24.4 Counting up to find a difference
Counting up to find a difference helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Beginner Note
Start with real objects, fingers, or a picture. Say the idea aloud, try one small example, and check it by counting or comparing again.
10 Worked Examples with Answers and Very-Beginner Explanations
Worked Example 1
Problem: What does Counting up to find a difference mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Counting up to find a difference helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Counting up to find a difference helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Worked Example 2
Problem: Show one small example of Counting up to find a difference.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Counting up to find a difference helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: A correct small model or drawing can show the meaning of Counting up to find a difference.
Worked Example 3
Problem: Which tool could help with Counting up to find a difference?
- Think about counters, fingers, a ten frame, number line, picture, table, or real object.
- Choose the tool that makes the idea easiest to see.
Very beginner explanation: Counting up to find a difference helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Use a simple tool that lets you see and check the quantities or shapes.
Worked Example 4
Problem: How can you check your work in Counting up to find a difference?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Counting up to find a difference helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Check by recounting, comparing, or using a second simple model.
Worked Example 5
Problem: Where might you use Counting up to find a difference in everyday life?
- Think about toys, snacks, books, classroom objects, calendars, shapes, or money.
- Choose one situation.
- Explain how the math helps.
Very beginner explanation: Counting up to find a difference helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Counting up to find a difference can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: Count to 6. What number comes just before 6?
- Count forward until 6.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 5
Worked Example 7
Problem: Count to 12. What number comes just before 12?
- Count forward until 12.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 11
Worked Example 8
Problem: Count to 19. What number comes just before 19?
- Count forward until 19.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 18
Worked Example 9
Problem: Count to 27. What number comes just before 27?
- Count forward until 27.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 26
Worked Example 10
Problem: Count to 44. What number comes just before 44?
- Count forward until 44.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 43
Practice Exercise
Create one small question about Counting up to find a difference. Show it with objects, a picture, or numbers, then check by counting or comparing again.
24.5 Using a ten frame
Using a ten frame is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Beginner Note
Start with real objects, fingers, or a picture. Say the idea aloud, try one small example, and check it by counting or comparing again.
10 Worked Examples with Answers and Very-Beginner Explanations
Worked Example 1
Problem: What does Using a ten frame mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Using a ten frame is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: Using a ten frame is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Worked Example 2
Problem: Show one small example of Using a ten frame.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Using a ten frame is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: A correct small model or drawing can show the meaning of Using a ten frame.
Worked Example 3
Problem: Which tool could help with Using a ten frame?
- Think about counters, fingers, a ten frame, number line, picture, table, or real object.
- Choose the tool that makes the idea easiest to see.
Very beginner explanation: Using a ten frame is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: Use a simple tool that lets you see and check the quantities or shapes.
Worked Example 4
Problem: How can you check your work in Using a ten frame?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Using a ten frame is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: Check by recounting, comparing, or using a second simple model.
Worked Example 5
Problem: Where might you use Using a ten frame in everyday life?
- Think about toys, snacks, books, classroom objects, calendars, shapes, or money.
- Choose one situation.
- Explain how the math helps.
Very beginner explanation: Using a ten frame is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: Using a ten frame can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: Show Using a ten frame with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Using a ten frame best through concrete examples and clear words.
Answer: A correct simple example of Using a ten frame.
Worked Example 7
Problem: Show Using a ten frame with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Using a ten frame best through concrete examples and clear words.
Answer: A correct simple example of Using a ten frame.
Worked Example 8
Problem: Show Using a ten frame with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Using a ten frame best through concrete examples and clear words.
Answer: A correct simple example of Using a ten frame.
Worked Example 9
Problem: Show Using a ten frame with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Using a ten frame best through concrete examples and clear words.
Answer: A correct simple example of Using a ten frame.
Worked Example 10
Problem: Show Using a ten frame with a simple Grade 1 example.
- Use small numbers, objects, or a drawing.
- Explain what the example shows.
Very beginner explanation: Grade 1 learners understand Using a ten frame best through concrete examples and clear words.
Answer: A correct simple example of Using a ten frame.
Practice Exercise
Create one small question about Using a ten frame. Show it with objects, a picture, or numbers, then check by counting or comparing again.
24.6 Using a number line
Using a number line helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Beginner Note
Start with real objects, fingers, or a picture. Say the idea aloud, try one small example, and check it by counting or comparing again.
10 Worked Examples with Answers and Very-Beginner Explanations
Worked Example 1
Problem: What does Using a number line mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Using a number line helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Using a number line helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Worked Example 2
Problem: Show one small example of Using a number line.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Using a number line helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: A correct small model or drawing can show the meaning of Using a number line.
Worked Example 3
Problem: Which tool could help with Using a number line?
- Think about counters, fingers, a ten frame, number line, picture, table, or real object.
- Choose the tool that makes the idea easiest to see.
Very beginner explanation: Using a number line helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Use a simple tool that lets you see and check the quantities or shapes.
Worked Example 4
Problem: How can you check your work in Using a number line?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Using a number line helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Check by recounting, comparing, or using a second simple model.
Worked Example 5
Problem: Where might you use Using a number line in everyday life?
- Think about toys, snacks, books, classroom objects, calendars, shapes, or money.
- Choose one situation.
- Explain how the math helps.
Very beginner explanation: Using a number line helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Using a number line can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: Count to 6. What number comes just before 6?
- Count forward until 6.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 5
Worked Example 7
Problem: Count to 12. What number comes just before 12?
- Count forward until 12.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 11
Worked Example 8
Problem: Count to 19. What number comes just before 19?
- Count forward until 19.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 18
Worked Example 9
Problem: Count to 27. What number comes just before 27?
- Count forward until 27.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 26
Worked Example 10
Problem: Count to 44. What number comes just before 44?
- Count forward until 44.
- Move back one number.
Very beginner explanation: The number before is one less.
Answer: 43
Practice Exercise
Create one small question about Using a number line. Show it with objects, a picture, or numbers, then check by counting or comparing again.
24.7 Using related addition facts
Using related addition facts teaches how to put quantities together. Learners use objects, drawings, ten frames, and counting-on strategies before writing number sentences.
Beginner Note
Start with real objects, fingers, or a picture. Say the idea aloud, try one small example, and check it by counting or comparing again.
10 Worked Examples with Answers and Very-Beginner Explanations
Worked Example 1
Problem: What does Using related addition facts mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Using related addition facts teaches how to put quantities together. Learners use objects, drawings, ten frames, and counting-on strategies before writing number sentences.
Answer: Using related addition facts teaches how to put quantities together. Learners use objects, drawings, ten frames, and counting-on strategies before writing number sentences.
Worked Example 2
Problem: Show one small example of Using related addition facts.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Using related addition facts teaches how to put quantities together. Learners use objects, drawings, ten frames, and counting-on strategies before writing number sentences.
Answer: A correct small model or drawing can show the meaning of Using related addition facts.
Worked Example 3
Problem: Which tool could help with Using related addition facts?
- Think about counters, fingers, a ten frame, number line, picture, table, or real object.
- Choose the tool that makes the idea easiest to see.
Very beginner explanation: Using related addition facts teaches how to put quantities together. Learners use objects, drawings, ten frames, and counting-on strategies before writing number sentences.
Answer: Use a simple tool that lets you see and check the quantities or shapes.
Worked Example 4
Problem: How can you check your work in Using related addition facts?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Using related addition facts teaches how to put quantities together. Learners use objects, drawings, ten frames, and counting-on strategies before writing number sentences.
Answer: Check by recounting, comparing, or using a second simple model.
Worked Example 5
Problem: Where might you use Using related addition facts in everyday life?
- Think about toys, snacks, books, classroom objects, calendars, shapes, or money.
- Choose one situation.
- Explain how the math helps.
Very beginner explanation: Using related addition facts teaches how to put quantities together. Learners use objects, drawings, ten frames, and counting-on strategies before writing number sentences.
Answer: Using related addition facts can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: Find 2 + 3.
- Make a group of 2.
- Add 3 more.
- Count all the objects.
Very beginner explanation: Addition puts quantities together.
Answer: 5
Worked Example 7
Problem: Find 4 + 1.
- Make a group of 4.
- Add 1 more.
- Count all the objects.
Very beginner explanation: Addition puts quantities together.
Answer: 5
Worked Example 8
Problem: Find 5 + 2.
- Make a group of 5.
- Add 2 more.
- Count all the objects.
Very beginner explanation: Addition puts quantities together.
Answer: 7
Worked Example 9
Problem: Find 6 + 3.
- Make a group of 6.
- Add 3 more.
- Count all the objects.
Very beginner explanation: Addition puts quantities together.
Answer: 9
Worked Example 10
Problem: Find 8 + 2.
- Make a group of 8.
- Add 2 more.
- Count all the objects.
Very beginner explanation: Addition puts quantities together.
Answer: 10
Practice Exercise
Create one small question about Using related addition facts. Show it with objects, a picture, or numbers, then check by counting or comparing again.
24.8 Choosing a subtraction strategy
Choosing a subtraction strategy teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Beginner Note
Start with real objects, fingers, or a picture. Say the idea aloud, try one small example, and check it by counting or comparing again.
10 Worked Examples with Answers and Very-Beginner Explanations
Worked Example 1
Problem: What does Choosing a subtraction strategy mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Choosing a subtraction strategy teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: Choosing a subtraction strategy teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Worked Example 2
Problem: Show one small example of Choosing a subtraction strategy.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Choosing a subtraction strategy teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: A correct small model or drawing can show the meaning of Choosing a subtraction strategy.
Worked Example 3
Problem: Which tool could help with Choosing a subtraction strategy?
- Think about counters, fingers, a ten frame, number line, picture, table, or real object.
- Choose the tool that makes the idea easiest to see.
Very beginner explanation: Choosing a subtraction strategy teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: Use a simple tool that lets you see and check the quantities or shapes.
Worked Example 4
Problem: How can you check your work in Choosing a subtraction strategy?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Choosing a subtraction strategy teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: Check by recounting, comparing, or using a second simple model.
Worked Example 5
Problem: Where might you use Choosing a subtraction strategy in everyday life?
- Think about toys, snacks, books, classroom objects, calendars, shapes, or money.
- Choose one situation.
- Explain how the math helps.
Very beginner explanation: Choosing a subtraction strategy teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: Choosing a subtraction strategy can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: Find 5 - 2.
- Start with 5 objects.
- Take away 2.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 3
Worked Example 7
Problem: Find 7 - 3.
- Start with 7 objects.
- Take away 3.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 4
Worked Example 8
Problem: Find 9 - 4.
- Start with 9 objects.
- Take away 4.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 5
Worked Example 9
Problem: Find 10 - 6.
- Start with 10 objects.
- Take away 6.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 4
Worked Example 10
Problem: Find 14 - 5.
- Start with 14 objects.
- Take away 5.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 9
Practice Exercise
Create one small question about Choosing a subtraction strategy. Show it with objects, a picture, or numbers, then check by counting or comparing again.
24.9 Checking subtraction
Checking subtraction teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Beginner Note
Start with real objects, fingers, or a picture. Say the idea aloud, try one small example, and check it by counting or comparing again.
10 Worked Examples with Answers and Very-Beginner Explanations
Worked Example 1
Problem: What does Checking subtraction mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Checking subtraction teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: Checking subtraction teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Worked Example 2
Problem: Show one small example of Checking subtraction.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Checking subtraction teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: A correct small model or drawing can show the meaning of Checking subtraction.
Worked Example 3
Problem: Which tool could help with Checking subtraction?
- Think about counters, fingers, a ten frame, number line, picture, table, or real object.
- Choose the tool that makes the idea easiest to see.
Very beginner explanation: Checking subtraction teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: Use a simple tool that lets you see and check the quantities or shapes.
Worked Example 4
Problem: How can you check your work in Checking subtraction?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Checking subtraction teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: Check by recounting, comparing, or using a second simple model.
Worked Example 5
Problem: Where might you use Checking subtraction in everyday life?
- Think about toys, snacks, books, classroom objects, calendars, shapes, or money.
- Choose one situation.
- Explain how the math helps.
Very beginner explanation: Checking subtraction teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: Checking subtraction can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: Find 5 - 2.
- Start with 5 objects.
- Take away 2.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 3
Worked Example 7
Problem: Find 7 - 3.
- Start with 7 objects.
- Take away 3.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 4
Worked Example 8
Problem: Find 9 - 4.
- Start with 9 objects.
- Take away 4.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 5
Worked Example 9
Problem: Find 10 - 6.
- Start with 10 objects.
- Take away 6.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 4
Worked Example 10
Problem: Find 14 - 5.
- Start with 14 objects.
- Take away 5.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 9
Practice Exercise
Create one small question about Checking subtraction. Show it with objects, a picture, or numbers, then check by counting or comparing again.
24.10 Subtraction-strategy review
Subtraction-strategy review teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Beginner Note
Start with real objects, fingers, or a picture. Say the idea aloud, try one small example, and check it by counting or comparing again.
10 Worked Examples with Answers and Very-Beginner Explanations
Worked Example 1
Problem: What does Subtraction-strategy review mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Subtraction-strategy review teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: Subtraction-strategy review teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Worked Example 2
Problem: Show one small example of Subtraction-strategy review.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Subtraction-strategy review teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: A correct small model or drawing can show the meaning of Subtraction-strategy review.
Worked Example 3
Problem: Which tool could help with Subtraction-strategy review?
- Think about counters, fingers, a ten frame, number line, picture, table, or real object.
- Choose the tool that makes the idea easiest to see.
Very beginner explanation: Subtraction-strategy review teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: Use a simple tool that lets you see and check the quantities or shapes.
Worked Example 4
Problem: How can you check your work in Subtraction-strategy review?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Subtraction-strategy review teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: Check by recounting, comparing, or using a second simple model.
Worked Example 5
Problem: Where might you use Subtraction-strategy review in everyday life?
- Think about toys, snacks, books, classroom objects, calendars, shapes, or money.
- Choose one situation.
- Explain how the math helps.
Very beginner explanation: Subtraction-strategy review teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Answer: Subtraction-strategy review can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: Find 5 - 2.
- Start with 5 objects.
- Take away 2.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 3
Worked Example 7
Problem: Find 7 - 3.
- Start with 7 objects.
- Take away 3.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 4
Worked Example 8
Problem: Find 9 - 4.
- Start with 9 objects.
- Take away 4.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 5
Worked Example 9
Problem: Find 10 - 6.
- Start with 10 objects.
- Take away 6.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 4
Worked Example 10
Problem: Find 14 - 5.
- Start with 14 objects.
- Take away 5.
- Count what is left.
Very beginner explanation: Subtraction tells how many are left or the difference.
Answer: 9
Practice Exercise
Create one small question about Subtraction-strategy review. Show it with objects, a picture, or numbers, then check by counting or comparing again.
Chapter Notes, Practice, and Common Mistakes
Chapter Notes
- Read or listen to the question before solving.
- Use objects, a drawing, ten frame, number line, table, graph, or simple number sentence when useful.
- Explain your thinking and check by counting, comparing, or using another simple model.
Extra Practice
- Create and solve one original problem about Taking away objects.
- Create and solve one original problem about Crossing out drawings.
- Create and solve one original problem about Counting back.
- Create and solve one original problem about Counting up to find a difference.
- Create and solve one original problem about Using a ten frame.
- Create and solve one original problem about Using a number line.
Common Mistakes
- Skipping the meaning and trying to memorize a rule only.
- Using the wrong operation because the question was not read completely.
- Ignoring units, labels, place values, or the context of the problem.
- Not estimating or checking whether the final answer is reasonable.
30 Review Questions and Answers
Q1. What is the main idea in Taking away objects?
Answer: Taking away objects is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Q2. What is the main idea in Crossing out drawings?
Answer: Crossing out drawings is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Q3. What is the main idea in Counting back?
Answer: Counting back helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Q4. What is the main idea in Counting up to find a difference?
Answer: Counting up to find a difference helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Q5. What is the main idea in Using a ten frame?
Answer: Using a ten frame is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Q6. What is the main idea in Using a number line?
Answer: Using a number line helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Q7. What is the main idea in Using related addition facts?
Answer: Using related addition facts teaches how to put quantities together. Learners use objects, drawings, ten frames, and counting-on strategies before writing number sentences.
Q8. What is the main idea in Choosing a subtraction strategy?
Answer: Choosing a subtraction strategy teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Q9. What is the main idea in Checking subtraction?
Answer: Checking subtraction teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Q10. What is the main idea in Subtraction-strategy review?
Answer: Subtraction-strategy review teaches how to take away or find what is left. Learners use objects, drawings, and counting strategies to make the meaning clear.
Q11. Why is it useful to use counters or drawings?
Answer: They make the quantities visible and help you understand before using only numbers.
Q12. Why should you count carefully?
Answer: Careful counting means each object is counted once and no object is missed.
Q13. What can you do if a problem feels hard?
Answer: Use smaller numbers, draw a picture, use objects, and solve one small step at a time.
Q14. Why should both sides of an equals sign match?
Answer: The equals sign means the two sides have the same value.
Q15. How can a number line help?
Answer: It shows number order and can help you count forward or backward.
Q16. How can a ten frame help?
Answer: It organizes objects into groups that make numbers and addition easier to see.
Q17. Why are equal shares important?
Answer: Equal shares make fair groups or equal parts.
Q18. How do patterns help us predict?
Answer: A pattern rule tells us what should come next.
Q19. Why do we label a graph or table?
Answer: Labels tell us what the information represents.
Q20. How can you describe a shape?
Answer: Talk about its sides, corners, flat or curved surfaces, and other visible attributes.
Q21. How can you compare two objects?
Answer: Choose one attribute, such as length, mass, or capacity, and compare that same attribute.
Q22. Why is a calendar useful?
Answer: It organizes days, weeks, months, dates, and events.
Q23. Why does money have different values?
Answer: Different coins and bills represent different amounts of money.
Q24. Why should you explain your answer?
Answer: Explaining shows how you thought about the problem and helps you check your reasoning.
Q25. What should you do after a mistake?
Answer: Look at the step again, fix it, and try a similar example.
Q26. How can you be a confident math learner?
Answer: Use positive self-talk, try a strategy, ask questions, and remember that mistakes help you learn.
Q27. When should you use a picture?
Answer: Use a picture when it helps you see quantities, shapes, positions, or a story problem.
Q28. When should you use objects?
Answer: Use objects when you want to count, join, take away, share, sort, or compare in a hands-on way.
Q29. How can you check addition?
Answer: Recount the combined objects or use another model.
Q30. How can you check subtraction?
Answer: Put the taken-away part and the part left back together to see if they make the starting amount.