Chapter 15: Tens and Ones
Learn Grade 1 mathematics from very beginner explanations through worked examples, practice, reasoning, and review.
Chapter Overview
This chapter teaches Tens and Ones with simple language, step-by-step reasoning, and original worked examples. Math words are explained in simple Grade 1 language.
Key Technical Terms
- Understanding a group of ten (a Grade 1 idea used in this chapter)
- Understanding ones (a Grade 1 idea used in this chapter)
- Building 10 with ones (a Grade 1 idea used in this chapter)
- Building teen numbers with tens and ones (a Grade 1 idea used in this chapter)
- Building numbers to 50 (a Grade 1 idea used in this chapter)
- Reading a tens-and-ones model (a Grade 1 idea used in this chapter)
- Drawing tens and ones (a Grade 1 idea used in this chapter)
- Breaking numbers into tens and ones (a Grade 1 idea used in this chapter)
- Trading 10 ones for 1 ten (a Grade 1 idea used in this chapter)
- Tens and ones 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.
15.1 Understanding a group of ten
Understanding a group of ten 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 Understanding a group of ten mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Understanding a group of ten is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: Understanding a group of ten 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 Understanding a group of ten.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Understanding a group of ten 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 Understanding a group of ten.
Worked Example 3
Problem: Which tool could help with Understanding a group of ten?
- 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: Understanding a group of ten 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 Understanding a group of ten?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Understanding a group of ten 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 Understanding a group of ten 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: Understanding a group of ten is a Grade 1 mathematics idea. Learn it with objects or pictures first, then explain it with numbers or words.
Answer: Understanding a group of ten can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: Count by 10 from 0 to 10.
- Start at 0.
- Add 10 each time.
Very beginner explanation: Counting by 10 follows the tens.
Answer: 0, 10
Worked Example 7
Problem: Count by 10 from 0 to 20.
- Start at 0.
- Add 10 each time.
Very beginner explanation: Counting by 10 follows the tens.
Answer: 0, 10, 20
Worked Example 8
Problem: Count by 10 from 0 to 30.
- Start at 0.
- Add 10 each time.
Very beginner explanation: Counting by 10 follows the tens.
Answer: 0, 10, 20, 30
Worked Example 9
Problem: Count by 10 from 0 to 40.
- Start at 0.
- Add 10 each time.
Very beginner explanation: Counting by 10 follows the tens.
Answer: 0, 10, 20, 30, 40
Worked Example 10
Problem: Count by 10 from 0 to 50.
- Start at 0.
- Add 10 each time.
Very beginner explanation: Counting by 10 follows the tens.
Answer: 0, 10, 20, 30, 40, 50
Practice Exercise
Create one small question about Understanding a group of ten. Show it with objects, a picture, or numbers, then check by counting or comparing again.
15.2 Understanding ones
Understanding ones 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 Understanding ones mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Understanding ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Understanding ones 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 Understanding ones.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Understanding ones 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 Understanding ones.
Worked Example 3
Problem: Which tool could help with Understanding ones?
- 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: Understanding ones 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 Understanding ones?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Understanding ones 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 Understanding ones 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: Understanding ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Understanding ones can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: How many tens and ones are in 10?
- 10 has 1 full group(s) of ten.
- 0 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 0 ones
Worked Example 7
Problem: How many tens and ones are in 12?
- 12 has 1 full group(s) of ten.
- 2 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 2 ones
Worked Example 8
Problem: How many tens and ones are in 19?
- 19 has 1 full group(s) of ten.
- 9 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 9 ones
Worked Example 9
Problem: How many tens and ones are in 27?
- 27 has 2 full group(s) of ten.
- 7 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 2 tens and 7 ones
Worked Example 10
Problem: How many tens and ones are in 44?
- 44 has 4 full group(s) of ten.
- 4 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 4 tens and 4 ones
Practice Exercise
Create one small question about Understanding ones. Show it with objects, a picture, or numbers, then check by counting or comparing again.
15.3 Building 10 with ones
Building 10 with ones 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 Building 10 with ones mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Building 10 with ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Building 10 with ones 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 Building 10 with ones.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Building 10 with ones 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 Building 10 with ones.
Worked Example 3
Problem: Which tool could help with Building 10 with ones?
- 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: Building 10 with ones 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 Building 10 with ones?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Building 10 with ones 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 Building 10 with ones 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: Building 10 with ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Building 10 with ones can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: How many tens and ones are in 10?
- 10 has 1 full group(s) of ten.
- 0 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 0 ones
Worked Example 7
Problem: How many tens and ones are in 12?
- 12 has 1 full group(s) of ten.
- 2 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 2 ones
Worked Example 8
Problem: How many tens and ones are in 19?
- 19 has 1 full group(s) of ten.
- 9 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 9 ones
Worked Example 9
Problem: How many tens and ones are in 27?
- 27 has 2 full group(s) of ten.
- 7 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 2 tens and 7 ones
Worked Example 10
Problem: How many tens and ones are in 44?
- 44 has 4 full group(s) of ten.
- 4 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 4 tens and 4 ones
Practice Exercise
Create one small question about Building 10 with ones. Show it with objects, a picture, or numbers, then check by counting or comparing again.
15.4 Building teen numbers with tens and ones
Building teen numbers with tens and ones 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 Building teen numbers with tens and ones mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Building teen numbers with tens and ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Building teen numbers with tens and ones 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 Building teen numbers with tens and ones.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Building teen numbers with tens and ones 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 Building teen numbers with tens and ones.
Worked Example 3
Problem: Which tool could help with Building teen numbers with tens and ones?
- 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: Building teen numbers with tens and ones 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 Building teen numbers with tens and ones?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Building teen numbers with tens and ones 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 Building teen numbers with tens and ones 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: Building teen numbers with tens and ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Building teen numbers with tens and ones can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: How many tens and ones are in 10?
- 10 has 1 full group(s) of ten.
- 0 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 0 ones
Worked Example 7
Problem: How many tens and ones are in 12?
- 12 has 1 full group(s) of ten.
- 2 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 2 ones
Worked Example 8
Problem: How many tens and ones are in 19?
- 19 has 1 full group(s) of ten.
- 9 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 9 ones
Worked Example 9
Problem: How many tens and ones are in 27?
- 27 has 2 full group(s) of ten.
- 7 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 2 tens and 7 ones
Worked Example 10
Problem: How many tens and ones are in 44?
- 44 has 4 full group(s) of ten.
- 4 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 4 tens and 4 ones
Practice Exercise
Create one small question about Building teen numbers with tens and ones. Show it with objects, a picture, or numbers, then check by counting or comparing again.
15.5 Building numbers to 50
Building numbers to 50 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 Building numbers to 50 mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Building numbers to 50 helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Building numbers to 50 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 Building numbers to 50.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Building numbers to 50 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 Building numbers to 50.
Worked Example 3
Problem: Which tool could help with Building numbers to 50?
- 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: Building numbers to 50 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 Building numbers to 50?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Building numbers to 50 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 Building numbers to 50 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: Building numbers to 50 helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Building numbers to 50 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 Building numbers to 50. Show it with objects, a picture, or numbers, then check by counting or comparing again.
15.6 Reading a tens-and-ones model
Reading a tens-and-ones model 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 Reading a tens-and-ones model mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Reading a tens-and-ones model helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Reading a tens-and-ones model 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 Reading a tens-and-ones model.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Reading a tens-and-ones model 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 Reading a tens-and-ones model.
Worked Example 3
Problem: Which tool could help with Reading a tens-and-ones model?
- 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: Reading a tens-and-ones model 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 Reading a tens-and-ones model?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Reading a tens-and-ones model 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 Reading a tens-and-ones model 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: Reading a tens-and-ones model helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Reading a tens-and-ones model can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: How many tens and ones are in 10?
- 10 has 1 full group(s) of ten.
- 0 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 0 ones
Worked Example 7
Problem: How many tens and ones are in 12?
- 12 has 1 full group(s) of ten.
- 2 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 2 ones
Worked Example 8
Problem: How many tens and ones are in 19?
- 19 has 1 full group(s) of ten.
- 9 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 9 ones
Worked Example 9
Problem: How many tens and ones are in 27?
- 27 has 2 full group(s) of ten.
- 7 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 2 tens and 7 ones
Worked Example 10
Problem: How many tens and ones are in 44?
- 44 has 4 full group(s) of ten.
- 4 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 4 tens and 4 ones
Practice Exercise
Create one small question about Reading a tens-and-ones model. Show it with objects, a picture, or numbers, then check by counting or comparing again.
15.7 Drawing tens and ones
Drawing tens and ones 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 Drawing tens and ones mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Drawing tens and ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Drawing tens and ones 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 Drawing tens and ones.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Drawing tens and ones 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 Drawing tens and ones.
Worked Example 3
Problem: Which tool could help with Drawing tens and ones?
- 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: Drawing tens and ones 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 Drawing tens and ones?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Drawing tens and ones 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 Drawing tens and ones 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: Drawing tens and ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Drawing tens and ones can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: How many tens and ones are in 10?
- 10 has 1 full group(s) of ten.
- 0 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 0 ones
Worked Example 7
Problem: How many tens and ones are in 12?
- 12 has 1 full group(s) of ten.
- 2 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 2 ones
Worked Example 8
Problem: How many tens and ones are in 19?
- 19 has 1 full group(s) of ten.
- 9 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 9 ones
Worked Example 9
Problem: How many tens and ones are in 27?
- 27 has 2 full group(s) of ten.
- 7 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 2 tens and 7 ones
Worked Example 10
Problem: How many tens and ones are in 44?
- 44 has 4 full group(s) of ten.
- 4 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 4 tens and 4 ones
Practice Exercise
Create one small question about Drawing tens and ones. Show it with objects, a picture, or numbers, then check by counting or comparing again.
15.8 Breaking numbers into tens and ones
Breaking numbers into tens and ones 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 Breaking numbers into tens and ones mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Breaking numbers into tens and ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Breaking numbers into tens and ones 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 Breaking numbers into tens and ones.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Breaking numbers into tens and ones 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 Breaking numbers into tens and ones.
Worked Example 3
Problem: Which tool could help with Breaking numbers into tens and ones?
- 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: Breaking numbers into tens and ones 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 Breaking numbers into tens and ones?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Breaking numbers into tens and ones 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 Breaking numbers into tens and ones 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: Breaking numbers into tens and ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Breaking numbers into tens and ones can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: How many tens and ones are in 10?
- 10 has 1 full group(s) of ten.
- 0 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 0 ones
Worked Example 7
Problem: How many tens and ones are in 12?
- 12 has 1 full group(s) of ten.
- 2 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 2 ones
Worked Example 8
Problem: How many tens and ones are in 19?
- 19 has 1 full group(s) of ten.
- 9 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 9 ones
Worked Example 9
Problem: How many tens and ones are in 27?
- 27 has 2 full group(s) of ten.
- 7 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 2 tens and 7 ones
Worked Example 10
Problem: How many tens and ones are in 44?
- 44 has 4 full group(s) of ten.
- 4 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 4 tens and 4 ones
Practice Exercise
Create one small question about Breaking numbers into tens and ones. Show it with objects, a picture, or numbers, then check by counting or comparing again.
15.9 Trading 10 ones for 1 ten
Trading 10 ones for 1 ten 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 Trading 10 ones for 1 ten mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Trading 10 ones for 1 ten helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Trading 10 ones for 1 ten 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 Trading 10 ones for 1 ten.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Trading 10 ones for 1 ten 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 Trading 10 ones for 1 ten.
Worked Example 3
Problem: Which tool could help with Trading 10 ones for 1 ten?
- 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: Trading 10 ones for 1 ten 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 Trading 10 ones for 1 ten?
- Look at the objects, drawing, or numbers again.
- Count or compare one more time.
- Make sure the answer matches the question.
Very beginner explanation: Trading 10 ones for 1 ten 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 Trading 10 ones for 1 ten 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: Trading 10 ones for 1 ten helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Trading 10 ones for 1 ten can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: How many tens and ones are in 10?
- 10 has 1 full group(s) of ten.
- 0 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 0 ones
Worked Example 7
Problem: How many tens and ones are in 12?
- 12 has 1 full group(s) of ten.
- 2 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 2 ones
Worked Example 8
Problem: How many tens and ones are in 19?
- 19 has 1 full group(s) of ten.
- 9 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 9 ones
Worked Example 9
Problem: How many tens and ones are in 27?
- 27 has 2 full group(s) of ten.
- 7 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 2 tens and 7 ones
Worked Example 10
Problem: How many tens and ones are in 44?
- 44 has 4 full group(s) of ten.
- 4 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 4 tens and 4 ones
Practice Exercise
Create one small question about Trading 10 ones for 1 ten. Show it with objects, a picture, or numbers, then check by counting or comparing again.
15.10 Tens and ones review
Tens and ones review 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 Tens and ones review mean?
- Say the topic in simple words.
- Use objects, fingers, a drawing, or a number example.
- Tell what you notice.
Very beginner explanation: Tens and ones review helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Tens and ones review 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 Tens and ones review.
- Choose small numbers or a simple shape/object.
- Make a model or drawing.
- Describe what the model shows.
Very beginner explanation: Tens and ones review 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 Tens and ones review.
Worked Example 3
Problem: Which tool could help with Tens and ones 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: Tens and ones review 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 Tens and ones 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: Tens and ones review 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 Tens and ones 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: Tens and ones review helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Answer: Tens and ones review can help with a simple everyday task such as counting, sharing, comparing, measuring, organizing, or deciding.
Worked Example 6
Problem: How many tens and ones are in 10?
- 10 has 1 full group(s) of ten.
- 0 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 0 ones
Worked Example 7
Problem: How many tens and ones are in 12?
- 12 has 1 full group(s) of ten.
- 2 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 2 ones
Worked Example 8
Problem: How many tens and ones are in 19?
- 19 has 1 full group(s) of ten.
- 9 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 1 tens and 9 ones
Worked Example 9
Problem: How many tens and ones are in 27?
- 27 has 2 full group(s) of ten.
- 7 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 2 tens and 7 ones
Worked Example 10
Problem: How many tens and ones are in 44?
- 44 has 4 full group(s) of ten.
- 4 object(s) are left as ones.
Very beginner explanation: Groups of ten and leftover ones show place value.
Answer: 4 tens and 4 ones
Practice Exercise
Create one small question about Tens and ones 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 Understanding a group of ten.
- Create and solve one original problem about Understanding ones.
- Create and solve one original problem about Building 10 with ones.
- Create and solve one original problem about Building teen numbers with tens and ones.
- Create and solve one original problem about Building numbers to 50.
- Create and solve one original problem about Reading a tens-and-ones model.
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 Understanding a group of ten?
Answer: Understanding a group of ten 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 Understanding ones?
Answer: Understanding ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Q3. What is the main idea in Building 10 with ones?
Answer: Building 10 with ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Q4. What is the main idea in Building teen numbers with tens and ones?
Answer: Building teen numbers with tens and ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Q5. What is the main idea in Building numbers to 50?
Answer: Building numbers to 50 helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Q6. What is the main idea in Reading a tens-and-ones model?
Answer: Reading a tens-and-ones model helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Q7. What is the main idea in Drawing tens and ones?
Answer: Drawing tens and ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Q8. What is the main idea in Breaking numbers into tens and ones?
Answer: Breaking numbers into tens and ones helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Q9. What is the main idea in Trading 10 ones for 1 ten?
Answer: Trading 10 ones for 1 ten helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
Q10. What is the main idea in Tens and ones review?
Answer: Tens and ones review helps Grade 1 learners build strong number sense with small numbers, objects, drawings, and number lines.
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.