Reception Maths: Parts and wholes
Part of the Reception Maths making and splitting numbers chapter. Chapter overview · whole chapter on one page
Parts and wholes
Lily has 5 cubes. Some are red and some are blue.
The whole is all the cubes together. The parts are the groups that make the whole. Two parts put together make the whole. The whole is always bigger than either part.
Key ideas
- The whole is all of the things together.
- The parts make the whole when they are put together.
- If you know one part and the whole, you can find the other part.
Key words. The whole is all of the things. The parts are the groups that make it.
Method. Put the two parts together, then count them all.
- Find the first part: 2. Start with the bigger part and count on.2
- Count on 3 more. Count on one at a time from the first part.2 + 3 = 5
- Write the answer. The total is the whole.5
Check. Count the whole group one at a time: 5. ✓
Watch out. Count on from the bigger part. The total is always bigger than either part.
Key words. A missing part is the number we add to the known part to make the whole.
Method. The whole is 4. One part is 1. Find the other part.
- Start with the whole: 4. The whole has all the things.4
- Take away the part you know: 1. What is left is the other part.4 − 1 = 3
- Check by counting on. 1 and 3 must make 4.1 + 3 = 4
- Write the answer. 3
Check. Count on from 1 to 4: 3 more. ✓
Watch out. Count on from the part you know, to reach the whole.
Key words. The whole is all of the things. The parts are the groups that make it.
Method. Put the two parts together, then count them all.
- Find the first part: 3. Start with the bigger part and count on.3
- Count on 2 more. Count on one at a time from the first part.3 + 2 = 5
- Write the answer. The total is the whole.5
Check. Count the whole group one at a time: 5. ✓
Watch out. Count on from the bigger part. The total is always bigger than either part.
Watch out
Watch out: the whole is always the biggest number. A part can never be bigger than the whole.
Exam tip
Grown-up tip. Use five cubes or buttons, two in one hand and three in the other. Ask: “How many altogether? How many in each hand?” Then hide one hand and ask how many are in it.
Exercise 4A Parts and wholes
Non-calculatorKey words. The whole is all of the things. The parts are the groups that make it.
Method. Put the two parts together, then count them all.
- Find the first part: 1. Start with the bigger part and count on.1
- Count on 2 more. Count on one at a time from the first part.1 + 2 = 3
- Write the answer. The total is the whole.3
Check. Count the whole group one at a time: 3. ✓
Watch out. Count on from the bigger part. The total is always bigger than either part.
Key words. The whole is all of the things. The parts are the groups that make it.
Method. Put the two parts together, then count them all.
- Find the first part: 2. Start with the bigger part and count on.2
- Count on 3 more. Count on one at a time from the first part.2 + 3 = 5
- Write the answer. The total is the whole.5
Check. Count the whole group one at a time: 5. ✓
Watch out. Count on from the bigger part. The total is always bigger than either part.
Key words. A missing part is the number we add to the known part to make the whole.
Method. The whole is 4. One part is 1. Find the other part.
- Start with the whole: 4. The whole has all the things.4
- Take away the part you know: 1. What is left is the other part.4 − 1 = 3
- Check by counting on. 1 and 3 must make 4.1 + 3 = 4
- Write the answer. 3
Check. Count on from 1 to 4: 3 more. ✓
Watch out. Count on from the part you know, to reach the whole.
Key words. A missing part is the number we add to the known part to make the whole.
Method. The whole is 6. One part is 2. Find the other part.
- Start with the whole: 6. The whole has all the things.6
- Take away the part you know: 2. What is left is the other part.6 − 2 = 4
- Check by counting on. 2 and 4 must make 6.2 + 4 = 6
- Write the answer. 4
Check. Count on from 2 to 6: 4 more. ✓
Watch out. Count on from the part you know, to reach the whole.
Key words. A missing part is the number we add to the known part to make the whole.
Method. The whole is 7. One part is 3. Find the other part.
- Start with the whole: 7. The whole has all the things.7
- Take away the part you know: 3. What is left is the other part.7 − 3 = 4
- Check by counting on. 3 and 4 must make 7.3 + 4 = 7
- Write the answer. 4
Check. Count on from 3 to 7: 4 more. ✓
Watch out. Count on from the part you know, to reach the whole.
Key words. A missing part is the number we add to the known part to make the whole.
Method. The whole is 8. One part is 5. Find the other part.
- Start with the whole: 8. The whole has all the things.8
- Take away the part you know: 5. What is left is the other part.8 − 5 = 3
- Check by counting on. 5 and 3 must make 8.5 + 3 = 8
- Write the answer. 3
Check. Count on from 5 to 8: 3 more. ✓
Watch out. Count on from the part you know, to reach the whole.
Key words. The whole is all of the things. The parts are the groups that make it.
Method. Put the two parts together, then count them all.
- Find the first part: 2. Start with the bigger part and count on.2
- Count on 4 more. Count on one at a time from the first part.2 + 4 = 6
- Write the answer. The total is the whole.6
Check. Count the whole group one at a time: 6. ✓
Watch out. Count on from the bigger part. The total is always bigger than either part.
Key words. The whole is all of the things. The parts are the groups that make it.
Method. Put the two parts together, then count them all.
- Find the first part: 3. Start with the bigger part and count on.3
- Count on 5 more. Count on one at a time from the first part.3 + 5 = 8
- Write the answer. The total is the whole.8
Check. Count the whole group one at a time: 8. ✓
Watch out. Count on from the bigger part. The total is always bigger than either part.
Key words. A missing part is the number we add to the known part to make the whole.
Method. The whole is 9. One part is 4. Find the other part.
- Start with the whole: 9. The whole has all the things.9
- Take away the part you know: 4. What is left is the other part.9 − 4 = 5
- Check by counting on. 4 and 5 must make 9.4 + 5 = 9
- Write the answer. 5
Check. Count on from 4 to 9: 5 more. ✓
Watch out. Count on from the part you know, to reach the whole.
Key words. A missing part is the number we add to the known part to make the whole.
Method. The whole is 10. One part is 6. Find the other part.
- Start with the whole: 10. The whole has all the things.10
- Take away the part you know: 6. What is left is the other part.10 − 6 = 4
- Check by counting on. 6 and 4 must make 10.6 + 4 = 10
- Write the answer. 4
Check. Count on from 6 to 10: 4 more. ✓
Watch out. Count on from the part you know, to reach the whole.
Key words. The whole is all of the things. The parts are the groups that make it.
Method. Put the two parts together, then count them all.
- Find the first part: 3. Start with the bigger part and count on.3
- Count on 4 more. Count on one at a time from the first part.3 + 4 = 7
- Write the answer. The total is the whole.7
Check. Count the whole group one at a time: 7. ✓
Watch out. Count on from the bigger part. The total is always bigger than either part.
Method. Count 2 and 2 together.
- Count the first part. Two things.2
- Count the second part. Two more things.2
- Put them together. Count all the things.1, 2, 3, 4
- Write the answer. No. 2 and 2 make 4, not 5.
Check. Count 4 things in all: 1, 2, 3, 4. ✓
Watch out. Count all the things, do not guess.