Year 1: Part-whole and number bonds
Part of the Year 1 adding and subtracting within 10 chapter. Chapter overview · whole chapter on one page · Download worksheet (PDF) · Answers (PDF)
Part-whole and number bonds
A part-whole model shows how a whole is made of parts. The big circle at the top is the whole. The two small circles are the parts.
The two parts put together make the whole. If you take one part away from the whole, the other part is left.
Two numbers that make a total are called a number bond. Here, 3 and 4 are a number bond to 7.
Key ideas
- The whole is the big number at the top.
- The parts are the two smaller numbers below.
- Parts put together make the whole: 3 + 4 = 7.
- The whole take away one part leaves the other part: 7 − 3 = 4.
- A number bond to 10 is two numbers that make 10, such as 6 and 4.
Key words. A missing number is shown by a box. Find the number that makes the sentence true.
Method. Start at 5. Count on until you reach 8. The number of counts is the missing number.
- Start at 5, the number we know. Put your finger on it.Start: 5
- Count on to 8. Say each number as you count on.6, 7, 8
- Count how many numbers you said. That many is the missing number.3 numbers
- Write the missing number. 3
Check. 5 + 3 = 8. ✓
Watch out. Count the numbers after 5, not 5 itself.
Key words. A missing number is shown by a box. Find the number that makes the sentence true.
Method. Start at 6. Count on until you reach 10. The number of counts is the missing number.
- Start at 6, the number we know. Put your finger on it.Start: 6
- Count on to 10. Say each number as you count on.7, 8, 9, 10
- Count how many numbers you said. That many is the missing number.4 numbers
- Write the missing number. 4
Check. 6 + 4 = 10. ✓
Watch out. Count the numbers after 6, not 6 itself.
Key words. To add is to put groups together. Count on means keep going up from a number.
Method. Start at the bigger number, then count on the smaller number.
- Start at the bigger number, 5. It is quicker to start with the bigger number.Start: 5
- Count on 4 more. Say one number for each step on.5, then 6, 7, 8, 9
- Write the total. The last number you say is the total.9
Check. Count all 9 things one at a time. You get 9 again. ✓
Watch out. Do not say the starting number again. Start with the next number after it.
Watch out
Watch out: a part is always smaller than the whole. If the whole is 8 and one part is 5, the other part is 3, not 13. Count on from the part you know until you reach the whole.
Exam tip
Grown-up tip. Draw a circle on paper for the whole and two circles for the parts. Hide some small toys in one hand and ask: “I have 10 toys. I can see 6. How many are hidden?” Then check by counting.
Exercise 2C Part-whole and number bonds
Non-calculatorKey words. A missing number is shown by a box. Find the number that makes the sentence true.
Method. Start at 2. Count on until you reach 5. The number of counts is the missing number.
- Start at 2, the number we know. Put your finger on it.Start: 2
- Count on to 5. Say each number as you count on.3, 4, 5
- Count how many numbers you said. That many is the missing number.3 numbers
- Write the missing number. 3
Check. 2 + 3 = 5. ✓
Watch out. Count the numbers after 2, not 2 itself.
Key words. A missing number is shown by a box. Find the number that makes the sentence true.
Method. Start at 4. Count on until you reach 9. The number of counts is the missing number.
- Start at 4, the number we know. Put your finger on it.Start: 4
- Count on to 9. Say each number as you count on.5, 6, 7, 8, 9
- Count how many numbers you said. That many is the missing number.5 numbers
- Write the missing number. 5
Check. 4 + 5 = 9. ✓
Watch out. Count the numbers after 4, not 4 itself.
Key words. A missing number is shown by a box. Find the number that makes the sentence true.
Method. Start at 7. Count on until you reach 10. The number of counts is the missing number.
- Start at 7, the number we know. Put your finger on it.Start: 7
- Count on to 10. Say each number as you count on.8, 9, 10
- Count how many numbers you said. That many is the missing number.3 numbers
- Write the missing number. 3
Check. 7 + 3 = 10. ✓
Watch out. Count the numbers after 7, not 7 itself.
Key words. To add is to put groups together. Count on means keep going up from a number.
Method. Start at the bigger number, then count on the smaller number.
- Start at the bigger number, 6. It is quicker to start with the bigger number.Start: 6
- Count on 3 more. Say one number for each step on.6, then 7, 8, 9
- Write the total. The last number you say is the total.9
Check. Count all 9 things one at a time. You get 9 again. ✓
Watch out. Do not say the starting number again. Start with the next number after it.
Key words. A missing number is shown by a box. Find the number that makes the sentence true.
Method. Start at 3. Count on until you reach 10. The number of counts is the missing number.
- Start at 3, the number we know. Put your finger on it.Start: 3
- Count on to 10. Say each number as you count on.4, 5, 6, 7, 8, 9, 10
- Count how many numbers you said. That many is the missing number.7 numbers
- Write the missing number. 7
Check. 3 + 7 = 10. ✓
Watch out. Count the numbers after 3, not 3 itself.
Key words. A missing number is shown by a box. Find the number that makes the sentence true.
Method. Start at 6. Count on until you reach 10. The number of counts is the missing number.
- Start at 6, the number we know. Put your finger on it.Start: 6
- Count on to 10. Say each number as you count on.7, 8, 9, 10
- Count how many numbers you said. That many is the missing number.4 numbers
- Write the missing number. 4
Check. 6 + 4 = 10. ✓
Watch out. Count the numbers after 6, not 6 itself.
Key words. A missing number is shown by a box. Find the number that makes the sentence true.
Method. Start at 8. Count on until you reach 10. The number of counts is the missing number.
- Start at 8, the number we know. Put your finger on it.Start: 8
- Count on to 10. Say each number as you count on.9, 10
- Count how many numbers you said. That many is the missing number.2 numbers
- Write the missing number. 2
Check. 8 + 2 = 10. ✓
Watch out. Count the numbers after 8, not 8 itself.
Key words. A missing number is shown by a box. Find the number that makes the sentence true.
Method. Start at 3. Count on until you reach 8. The number of counts is the missing number.
- Start at 3, the number we know. Put your finger on it.Start: 3
- Count on to 8. Say each number as you count on.4, 5, 6, 7, 8
- Count how many numbers you said. That many is the missing number.5 numbers
- Write the missing number. 5
Check. 3 + 5 = 8. ✓
Watch out. Count the numbers after 3, not 3 itself.
Key words. A missing number is shown by a box. Find the number that makes the sentence true.
Method. Start at 2. Count on until you reach 6. The number of counts is the missing number.
- Start at 2, the number we know. Put your finger on it.Start: 2
- Count on to 6. Say each number as you count on.3, 4, 5, 6
- Count how many numbers you said. That many is the missing number.4 numbers
- Write the missing number. 4
Check. 2 + 4 = 6. ✓
Watch out. Count the numbers after 2, not 2 itself.
Key words. A missing number is shown by a box. Find the number that makes the sentence true.
Method. Start at 4. Count on until you reach 10. The number of counts is the missing number.
- Start at 4, the number we know. Put your finger on it.Start: 4
- Count on to 10. Say each number as you count on.5, 6, 7, 8, 9, 10
- Count how many numbers you said. That many is the missing number.6 numbers
- Write the missing number. 6
Check. 4 + 6 = 10. ✓
Watch out. Count the numbers after 4, not 4 itself.
Key words. A missing number is shown by a box. Find the number that makes the sentence true.
Method. Start at 5. Count on until you reach 9. The number of counts is the missing number.
- Start at 5, the number we know. Put your finger on it.Start: 5
- Count on to 9. Say each number as you count on.6, 7, 8, 9
- Count how many numbers you said. That many is the missing number.4 numbers
- Write the missing number. 4
Check. 5 + 4 = 9. ✓
Watch out. Count the numbers after 5, not 5 itself.
Key words. A missing number is shown by a box. Find the number that makes the sentence true.
Method. Start at 2. Count on until you reach 7. The number of counts is the missing number.
- Start at 2, the number we know. Put your finger on it.Start: 2
- Count on to 7. Say each number as you count on.3, 4, 5, 6, 7
- Count how many numbers you said. That many is the missing number.5 numbers
- Write the missing number. 5
Check. 2 + 5 = 7. ✓
Watch out. Count the numbers after 2, not 2 itself.
Key words. The = sign means the two sides are the same amount.
Method. Work out 3 + 5, then check it against the number that was said.
- Work out 3 + 5. Start at the bigger number and count on.Start at 5, count on 3: 8
- Compare with what was said. Is the total the same as the number in the sentence?8 and 9
- Write the answer. No. 3 + 5 = 8.
Check. Count all the things: 3 + 5 = 8. ✓
Watch out. Work out the total first. Do not guess from the numbers you can see.