Year 1 Numbers to 20: worked examples and questions with answers
By the end of this chapter you will be able to
- Count forwards and backwards to 20
- Read and write the numbers 11 to 20 as numerals and as words
- Say how many tens and ones are in a number to 20, using a ten frame
- Say the number that is one more or one less, up to 20
- Count on and back along a number line to 20
- Say which of two numbers to 20 is bigger, and put them in order
You should already know
- Numbers 0 to 10 and their words (Chapter 1)
- Counting on and back within 10 (Chapter 1)
- Adding and subtracting within 10 (Chapter 2)
Where this leads
- Adding and subtracting within 20 (Chapter 5)
- Numbers to 100 (Chapter 6)
National Curriculum for England, Key Stage 1 mathematics, Year 1. Content: Count to and across 20, forwards and backwards, Count objects up to 20, Read and write numbers 11 to 20 as numerals and as words, Tens and ones with ten frames, One more and one less to 20, Use the number line to 20, Compare and order numbers to 20.
- 4.1 Counting to 20: Worksheet (PDF) · Answers (PDF) · lesson page
- 4.2 Reading and writing numbers 11 to 20: Worksheet (PDF) · Answers (PDF) · lesson page
- 4.3 Tens and ones with ten frames: Worksheet (PDF) · Answers (PDF) · lesson page
- 4.4 One more, one less and the number line to 20: Worksheet (PDF) · Answers (PDF) · lesson page
- 4.5 Comparing and ordering numbers to 20: Worksheet (PDF) · Answers (PDF) · lesson page
- Check-up and end-of-chapter quiz: Worksheet (PDF) · Answers (PDF) · lesson page
Exercise P Do you remember?
Non-calculatorKey words. One more is the next number. One less is the number just before.
Method. Start at 6. One more is the number after 6.
- Start at 6. Put your finger on the number.Start: 6
- Move one step forward. Each step on the number line is one number.6 + 1 = 7
- Write the answer. 7
Check. Check it: 7 − 1 = 6. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Method. Read the number word, then find it on the number list.
- Read the word. Read the whole word, not just the first letters.“eight”
- Find the word on the number list. Each word matches exactly one number.eight = 8
- Write the numeral. A numeral is the number written with digits.8
Check. Count 8 things. The last number you say is 8. ✓
Watch out. Look at the whole word, and check every letter.
Key words. To count is to say one number for each thing, in order: 1, 2, 3, and so on.
Method. Say one number for each one, and touch each one only once. The last number you say is how many there are.
- Count each one and say its number. Each one gets one number. Do not miss one and do not count one twice.1, 2, 3, 4, 5, 6, 7, 8, 9
- Look at the last number you said. The last number tells us how many there are altogether.The last number is 9.
- Write the answer. There are 9 stars.
Check. Count again from the other side. You get 9 again. ✓
Watch out. Move each one to one side as you count it, so you do not lose your place.
Method. The smallest number is the one furthest to the left on the number line.
- Find each number on the number line. Look at where each one sits.
- Find the smallest number. Smaller numbers are further left.4 is the smallest number.
- Write the answer. 4
Check. Compare 4 with each of the others: 4 < each one. ✓
Watch out. Do not look at the size of the writing. Compare the numbers.
Method. Count back from 5 to 1. Each number is one less than the number before it.
- Start at the first number. We start with the biggest number.5
- Take away one each time. Each number is one less than the one before.5, 4, 3, 2, 1
- Write the numbers. Include the start number and the end number.5, 4, 3, 2, 1
Check. Count on from 1 to 5 to check. ✓
Watch out. Count back in the same way each time. Do not skip a number, and do not say a number twice.
Counting to 20
Printable: Worksheet (PDF) · Answers (PDF) · Open this lesson on its own page
Let’s count past ten! After nine comes ten. After ten comes eleven, then twelve, and so on up to twenty.
When we count past ten, we start a new ten. The numbers from thirteen to nineteen are ten and some more.
We can also count backwards from twenty, one number at a time, all the way back down.
Counting across twenty means going past it: after twenty comes twenty-one, then twenty-two.
Key ideas
- Count forwards: each number is one more than the number before.
- Count backwards: each number is one less than the number before.
- After ten comes eleven. Start counting again from one more than ten.
- Teen numbers are ten and some more: 13 is ten and 3 more.
Key words. To count is to say one number for each thing, in order: 1, 2, 3, and so on.
Method. Say one number for each one, and touch each one only once. The last number you say is how many there are.
- Count each one and say its number. Each one gets one number. Do not miss one and do not count one twice.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14
- Look at the last number you said. The last number tells us how many there are altogether.The last number is 14.
- Write the answer. There are 14 apples.
Check. Count again from the other side. You get 14 again. ✓
Watch out. Move each one to one side as you count it, so you do not lose your place.
Method. Start at 15. Count on one number at a time until you reach 20.
- Start at 15. That is the first number you say.15
- Count on one at a time to 20. Each number is one more than the number before it.15, 16, 17, 18, 19, 20
- Write the numbers. Include the first number and the last number.15, 16, 17, 18, 19, 20
Check. Count back from 20 to 15 to check. ✓
Watch out. Do not skip a number when you go past ten. After nine comes ten, then eleven.
Method. Count back from 20 to 16. Each number is one less than the number before it.
- Start at the first number. We start with the biggest number.20
- Take away one each time. Each number is one less than the one before.20, 19, 18, 17, 16
- Write the numbers. Include the start number and the end number.20, 19, 18, 17, 16
Check. Count on from 16 to 20 to check. ✓
Watch out. Count back in the same way each time. Do not skip a number, and do not say a number twice.
Watch out
Watch out: do not skip a number when you count past ten. Count 18, 19, 20, not 18, 20. Check each number is one more than the one before.
Exam tip
Grown-up tip. Count the stairs, buttons or pasta shapes past ten. Ask: “What comes after nine?” and “What comes after nineteen?” Then count back from twenty together.
Exercise 4A Counting to 20
Non-calculatorKey words. To count is to say one number for each thing, in order: 1, 2, 3, and so on.
Method. Say one number for each one, and touch each one only once. The last number you say is how many there are.
- Count each one and say its number. Each one gets one number. Do not miss one and do not count one twice.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
- Look at the last number you said. The last number tells us how many there are altogether.The last number is 11.
- Write the answer. There are 11 balls.
Check. Count again from the other side. You get 11 again. ✓
Watch out. Move each one to one side as you count it, so you do not lose your place.
Key words. To count is to say one number for each thing, in order: 1, 2, 3, and so on.
Method. Say one number for each one, and touch each one only once. The last number you say is how many there are.
- Count each one and say its number. Each one gets one number. Do not miss one and do not count one twice.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
- Look at the last number you said. The last number tells us how many there are altogether.The last number is 16.
- Write the answer. There are 16 stars.
Check. Count again from the other side. You get 16 again. ✓
Watch out. Move each one to one side as you count it, so you do not lose your place.
Key words. To count is to say one number for each thing, in order: 1, 2, 3, and so on.
Method. Say one number for each one, and touch each one only once. The last number you say is how many there are.
- Count each one and say its number. Each one gets one number. Do not miss one and do not count one twice.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13
- Look at the last number you said. The last number tells us how many there are altogether.The last number is 13.
- Write the answer. There are 13 cubes.
Check. Count again from the other side. You get 13 again. ✓
Watch out. Move each one to one side as you count it, so you do not lose your place.
Key words. To count is to say one number for each thing, in order: 1, 2, 3, and so on.
Method. Say one number for each one, and touch each one only once. The last number you say is how many there are.
- Count each one and say its number. Each one gets one number. Do not miss one and do not count one twice.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20
- Look at the last number you said. The last number tells us how many there are altogether.The last number is 20.
- Write the answer. There are 20 apples.
Check. Count again from the other side. You get 20 again. ✓
Watch out. Move each one to one side as you count it, so you do not lose your place.
Method. Start at 12. Count on one number at a time until you reach 16.
- Start at 12. That is the first number you say.12
- Count on one at a time to 16. Each number is one more than the number before it.12, 13, 14, 15, 16
- Write the numbers. Include the first number and the last number.12, 13, 14, 15, 16
Check. Count back from 16 to 12 to check. ✓
Watch out. Do not skip a number when you go past ten. After nine comes ten, then eleven.
Method. Count back from 18 to 14. Each number is one less than the number before it.
- Start at the first number. We start with the biggest number.18
- Take away one each time. Each number is one less than the one before.18, 17, 16, 15, 14
- Write the numbers. Include the start number and the end number.18, 17, 16, 15, 14
Check. Count on from 14 to 18 to check. ✓
Watch out. Count back in the same way each time. Do not skip a number, and do not say a number twice.
Method. Start at 18. Count on one number at a time until you reach 22.
- Start at 18. That is the first number you say.18
- Count on one at a time to 22. Each number is one more than the number before it.18, 19, 20, 21, 22
- Write the numbers. Include the first number and the last number.18, 19, 20, 21, 22
Check. Count back from 22 to 18 to check. ✓
Watch out. Do not skip a number when you go past ten. After nine comes ten, then eleven.
Method. Start at 10. Count on one number at a time until you reach 20.
- Start at 10. That is the first number you say.10
- Count on one at a time to 20. Each number is one more than the number before it.10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20
- Write the numbers. Include the first number and the last number.10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20
Check. Count back from 20 to 10 to check. ✓
Watch out. Do not skip a number when you go past ten. After nine comes ten, then eleven.
Method. Each number is one more than the number before it. Use the numbers you can see to find the gaps.
- Look at the numbers before each gap. Counting on in ones means each number is one more than the one before.11, 12, ?, 14
- Count on one from the number before each gap. Add 1 to the number before the gap.Gap 3: 12 + 1 = 13
- Write the missing numbers. 13
Check. Read the whole line again: each number is one more than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go up by one.
Method. Each number is one more than the number before it. Use the numbers you can see to find the gaps.
- Look at the numbers before each gap. Counting on in ones means each number is one more than the one before.15, 16, ?, 18
- Count on one from the number before each gap. Add 1 to the number before the gap.Gap 3: 16 + 1 = 17
- Write the missing numbers. 17
Check. Read the whole line again: each number is one more than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go up by one.
Method. Each number is one more than the number before it. Use the numbers you can see to find the gaps.
- Look at the numbers before each gap. Counting on in ones means each number is one more than the one before.8, 9, 10, ?, 12
- Count on one from the number before each gap. Add 1 to the number before the gap.Gap 4: 10 + 1 = 11
- Write the missing numbers. 11
Check. Read the whole line again: each number is one more than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go up by one.
Method. Each number is one more than the number before it. Use the numbers you can see to find the gaps.
- Look at the numbers before each gap. Counting on in ones means each number is one more than the one before.15, 16, ?, 18
- Count on one from the number before each gap. Add 1 to the number before the gap.Gap 3: 16 + 1 = 17
- Write the missing numbers. 17
Check. Read the whole line again: each number is one more than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go up by one.
Method. Count back from 14 to 11. Each number is one less than the number before it.
- Start at the first number. We start with the biggest number.14
- Take away one each time. Each number is one less than the one before.14, 13, 12, 11
- Write the numbers. Include the start number and the end number.14, 13, 12, 11
Check. Count on from 11 to 14 to check. ✓
Watch out. Count back in the same way each time. Do not skip a number, and do not say a number twice.
Key words. To count is to say one number for each thing, in order: 1, 2, 3, and so on.
Method. Say one number for each one, and touch each one only once. The last number you say is how many there are.
- Count each one and say its number. Each one gets one number. Do not miss one and do not count one twice.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19
- Look at the last number you said. The last number tells us how many there are altogether.The last number is 19.
- Write the answer. There are 19 stars.
Check. Count again from the other side. You get 19 again. ✓
Watch out. Move each one to one side as you count it, so you do not lose your place.
Method. Count forwards from 9, then backwards from 12. Check each number is one more or one less than the one next to it.
- Count forwards from 9 to 12. Each number is one more than the one before.9, 10, 11, 12
- Count backwards from 12 to 9. Each number is one less than the one before.12, 11, 10, 9
- Check both ways. The same numbers appear in both lists, in opposite orders.Yes. Both ways are right.
Check. Count forwards and backwards along the same numbers. ✓
Watch out. Going up adds one each time. Going down takes one away each time.
Reading and writing numbers 11 to 20
Printable: Worksheet (PDF) · Answers (PDF) · Open this lesson on its own page
The numbers from eleven to twenty have names too. Learn them one at a time.
Eleven and twelve have names of their own. The numbers from thirteen to nineteen end in teen, which means “ten and some more”. Twenty comes after nineteen.
| Numeral | Word |
|---|---|
| 11 | eleven |
| 12 | twelve |
| 13 | thirteen |
| 14 | fourteen |
| 15 | fifteen |
| 16 | sixteen |
| 17 | seventeen |
| 18 | eighteen |
| 19 | nineteen |
| 20 | twenty |
Key ideas
- Eleven and twelve have their own names.
- The names from thirteen to nineteen end in teen.
- Twenty comes after nineteen.
- Read the whole word, then find its numeral.
Key words. A numeral is a number written with digits, like 14. A number word is its name, like fourteen.
Method. Say the number out loud, then write its name in words.
- Say the number. Listen to how it sounds.14
- Find its name on the number list. Every number has one name.14 = fourteen
- Write the word, one letter at a time. The word has 8 letters.fourteen
Check. Count out 14 things and say “fourteen” at the end. ✓
Watch out. Teen numbers end in teen. Check every letter of fourteen.
Method. Read the number word, then find it on the number list.
- Read the word. Read the whole word, not just the first letters.“seventeen”
- Find the word on the number list. Each word matches exactly one number.seventeen = 17
- Write the numeral. A numeral is the number written with digits.17
Check. Count 17 things. The last number you say is 17. ✓
Watch out. Teen numbers end in teen. Check every letter of seventeen.
Key words. A numeral is a number written with digits, like 14. A number word is its name, like fourteen.
Method. Say the number out loud, then write its name in words.
- Say the number. Listen to how it sounds.12
- Find its name on the number list. Every number has one name.12 = twelve
- Write the word, one letter at a time. The word has 6 letters.twelve
Check. Count out 12 things and say “twelve” at the end. ✓
Watch out. twelve does not end in teen. Learn it as its own name.
Watch out
Watch out: thirteen and thirty look alike. Thirteen ends in teen, so it is 13. Check the ending of the word before you write the numeral.
Exam tip
Grown-up tip. Say the number slowly and clap each part: thir-teen, four-teen, six-teen. Write the numeral and the word side by side, then check they match.
Exercise 4B Numerals and number words
Non-calculatorKey words. A numeral is a number written with digits, like 14. A number word is its name, like fourteen.
Method. Say the number out loud, then write its name in words.
- Say the number. Listen to how it sounds.11
- Find its name on the number list. Every number has one name.11 = eleven
- Write the word, one letter at a time. The word has 6 letters.eleven
Check. Count out 11 things and say “eleven” at the end. ✓
Watch out. eleven does not end in teen. Learn it as its own name.
Key words. A numeral is a number written with digits, like 14. A number word is its name, like fourteen.
Method. Say the number out loud, then write its name in words.
- Say the number. Listen to how it sounds.13
- Find its name on the number list. Every number has one name.13 = thirteen
- Write the word, one letter at a time. The word has 8 letters.thirteen
Check. Count out 13 things and say “thirteen” at the end. ✓
Watch out. Teen numbers end in teen. Check every letter of thirteen.
Key words. A numeral is a number written with digits, like 14. A number word is its name, like fourteen.
Method. Say the number out loud, then write its name in words.
- Say the number. Listen to how it sounds.15
- Find its name on the number list. Every number has one name.15 = fifteen
- Write the word, one letter at a time. The word has 7 letters.fifteen
Check. Count out 15 things and say “fifteen” at the end. ✓
Watch out. Teen numbers end in teen. Check every letter of fifteen.
Key words. A numeral is a number written with digits, like 14. A number word is its name, like fourteen.
Method. Say the number out loud, then write its name in words.
- Say the number. Listen to how it sounds.18
- Find its name on the number list. Every number has one name.18 = eighteen
- Write the word, one letter at a time. The word has 8 letters.eighteen
Check. Count out 18 things and say “eighteen” at the end. ✓
Watch out. Teen numbers end in teen. Check every letter of eighteen.
Method. Read the number word, then find it on the number list.
- Read the word. Read the whole word, not just the first letters.“twelve”
- Find the word on the number list. Each word matches exactly one number.twelve = 12
- Write the numeral. A numeral is the number written with digits.12
Check. Count 12 things. The last number you say is 12. ✓
Watch out. twelve does not end in teen. Learn it as its own name.
Method. Read the number word, then find it on the number list.
- Read the word. Read the whole word, not just the first letters.“sixteen”
- Find the word on the number list. Each word matches exactly one number.sixteen = 16
- Write the numeral. A numeral is the number written with digits.16
Check. Count 16 things. The last number you say is 16. ✓
Watch out. Teen numbers end in teen. Check every letter of sixteen.
Method. Read the number word, then find it on the number list.
- Read the word. Read the whole word, not just the first letters.“nineteen”
- Find the word on the number list. Each word matches exactly one number.nineteen = 19
- Write the numeral. A numeral is the number written with digits.19
Check. Count 19 things. The last number you say is 19. ✓
Watch out. Teen numbers end in teen. Check every letter of nineteen.
Method. Read the number word, then find it on the number list.
- Read the word. Read the whole word, not just the first letters.“fourteen”
- Find the word on the number list. Each word matches exactly one number.fourteen = 14
- Write the numeral. A numeral is the number written with digits.14
Check. Count 14 things. The last number you say is 14. ✓
Watch out. Teen numbers end in teen. Check every letter of fourteen.
Key words. A numeral is a number written with digits, like 14. A number word is its name, like fourteen.
Method. Say the number out loud, then write its name in words.
- Say the number. Listen to how it sounds.20
- Find its name on the number list. Every number has one name.20 = twenty
- Write the word, one letter at a time. The word has 6 letters.twenty
Check. Count out 20 things and say “twenty” at the end. ✓
Watch out. Twenty ends in ty, not teen. Check every letter.
Key words. A numeral is a number written with digits, like 14. A number word is its name, like fourteen.
Method. Say the number out loud, then write its name in words.
- Say the number. Listen to how it sounds.17
- Find its name on the number list. Every number has one name.17 = seventeen
- Write the word, one letter at a time. The word has 9 letters.seventeen
Check. Count out 17 things and say “seventeen” at the end. ✓
Watch out. Teen numbers end in teen. Check every letter of seventeen.
Method. Read the number word, then find it on the number list.
- Read the word. Read the whole word, not just the first letters.“fifteen”
- Find the word on the number list. Each word matches exactly one number.fifteen = 15
- Write the numeral. A numeral is the number written with digits.15
Check. Count 15 things. The last number you say is 15. ✓
Watch out. Teen numbers end in teen. Check every letter of fifteen.
Method. Start at 11. Count on one number at a time until you reach 15.
- Start at 11. That is the first number you say.11
- Count on one at a time to 15. Each number is one more than the number before it.11, 12, 13, 14, 15
- Write the numbers. Include the first number and the last number.11, 12, 13, 14, 15
Check. Count back from 15 to 11 to check. ✓
Watch out. Do not skip a number when you go past ten. After nine comes ten, then eleven.
Method. Read the number word, then find it on the number list.
- Read the word. Read the whole word, not just the first letters.“twelve”
- Find the word on the number list. Each word matches exactly one number.twelve = 12
- Write the numeral. A numeral is the number written with digits.12
Check. Count 12 things. The last number you say is 12. ✓
Watch out. twelve does not end in teen. Learn it as its own name.
Method. Read each word slowly, one letter at a time. Find the spelling that matches the number.
- Look at “sicteen”. Say the word slowly: six-teen. It has an x sound in the middle.sicteen is not right
- Find the right letters. Six is spelled s-i-x. Then add teen.s-i-x + t-e-e-n
- Write the word correctly. Put the letters together.sixteen
Check. Sixteen is 16. Count 16 things and say “sixteen”. ✓
Watch out. Six has an x in the middle. Do not write it as c or s.
Method. Find the number word that matches each numeral, then compare them.
- Look at thirteen. Thirteen is the number word for a number.thirteen = 13
- Look at 13. 13 is a numeral with the digits 1 and 3.13 = thirteen
- Look at eleven. Eleven is a different number from thirteen.eleven = 11, not 13
- Write the answer. Thirteen and 13 are the same number.thirteen and 13
Check. Thirteen and 13 are both the number 13. Eleven is 11. ✓
Watch out. A numeral and a number word can name the same number.
Method. Put the two numbers next to their numerals, then compare them.
- Look at twelve. Twelve is the number after eleven.twelve = 12
- Look at twenty. Twenty is the number after nineteen.twenty = 20
- Compare them. Both words start with tw, but the numbers are different.12 is not 20
Check. Count on from 12: 13, 14 ... 20. Twenty is further on. ✓
Watch out. Two words can start the same and still be different numbers.
Method. Think about what the word means. Eighteen means eight and ten more.
- Look at the word. Eighteen is made from eight and teen, which means ten more.eighteen = 8 and 10 more
- Add ten and eight. Ten and eight make eighteen.10 + 8 = 18
- Write the numeral. The numeral is written with digits.18
Check. Count on from ten: 11, 12, 13, 14, 15, 16, 17, 18. ✓
Watch out. Eighteen is not 81. The eight comes after the ten.
Tens and ones with ten frames
Printable: Worksheet (PDF) · Answers (PDF) · Open this lesson on its own page
A ten frame is a box with two rows of five spaces. It has ten spaces for counters. When all ten spaces are full, we have one ten.
For a teen number, we fill one ten frame, then put the rest on a second frame. The full ten is one ten. The counters that are left over are the ones.
So 13 is 1 ten and 3 ones.
Key ideas
- A ten frame has 10 spaces.
- A full ten frame is one ten.
- The counters left over are the ones.
- 13 is 1 ten and 3 ones.
Method. Count the full ten first, then count the ones that are left over.
- Find the full ten frame. A full ten frame has 10 counters. Start with ten, not with one.10 counters in the full tens
- Count the ones left over. These are the counters outside the full ten.6 ones
- Add them together. Ten and some more make a teen number.10 + 6 = 16
- Write the answer. 16
Check. Count all 16 counters one at a time. You get 16 again. ✓
Watch out. Start with ten, not with one. Then count on the ones.
Method. Start with the tens. Then add the ones.
- Start with the tens. One ten is 10 counters.1 ten = 10
- Add the ones. Count the ones on after the tens.10 + 4 = 14
- Write the answer. 14
Check. 1 ten and 4 ones is 14. ✓
Watch out. Do not write the tens and the ones next to each other. Add them to make one number.
Method. Count the full tens first. Then count the ones that are left.
- Count the tens. A ten is ten counters, or one full ten frame.1 ten = 10
- Count the ones. The ones are the counters that are left over.8 ones
- Write it with tens and ones. Say the tens first, then the ones.1 ten and 8 ones
Check. 10 + 8 = 18, so 18 is 1 ten and 8 ones. ✓
Watch out. Say the tens first, then the ones. One ten is 10, not 1.
Watch out
Watch out: count the full ten as ten, not as one. Do not count every counter in a full ten frame again. Start with ten, then count on the ones.
Exam tip
Grown-up tip. Draw a ten frame on paper: two rows of five boxes. Use buttons or dried pasta as counters. Ask your child to fill the first frame, then tell you how many tens and ones there are.
Exercise 4C Ten frames, tens and ones
Non-calculatorMethod. Count the full ten first, then count the ones that are left over.
- Find the full ten frame. A full ten frame has 10 counters. Start with ten, not with one.10 counters in the full tens
- Count the ones left over. These are the counters outside the full ten.1 one
- Add them together. Ten and some more make a teen number.10 + 1 = 11
- Write the answer. 11
Check. Count all 11 counters one at a time. You get 11 again. ✓
Watch out. Start with ten, not with one. Then count on the ones.
Method. Count the full ten first, then count the ones that are left over.
- Find the full ten frame. A full ten frame has 10 counters. Start with ten, not with one.10 counters in the full tens
- Count the ones left over. These are the counters outside the full ten.4 ones
- Add them together. Ten and some more make a teen number.10 + 4 = 14
- Write the answer. 14
Check. Count all 14 counters one at a time. You get 14 again. ✓
Watch out. Start with ten, not with one. Then count on the ones.
Method. Count the full ten first, then count the ones that are left over.
- Find the full ten frame. A full ten frame has 10 counters. Start with ten, not with one.10 counters in the full tens
- Count the ones left over. These are the counters outside the full ten.7 ones
- Add them together. Ten and some more make a teen number.10 + 7 = 17
- Write the answer. 17
Check. Count all 17 counters one at a time. You get 17 again. ✓
Watch out. Start with ten, not with one. Then count on the ones.
Method. Count the full ten first, then count the ones that are left over.
- Find the full ten frame. A full ten frame has 10 counters. Start with ten, not with one.20 counters in the full tens
- Count the ones left over. These are the counters outside the full ten.0 ones
- Add them together. Ten and some more make a teen number.20 + 0 = 20
- Write the answer. 20
Check. Count all 20 counters one at a time. You get 20 again. ✓
Watch out. Start with ten, not with one. Then count on the ones.
Method. Start with the tens. Then add the ones.
- Start with the tens. One ten is 10 counters.1 ten = 10
- Add the ones. Count the ones on after the tens.10 + 2 = 12
- Write the answer. 12
Check. 1 ten and 2 ones is 12. ✓
Watch out. Do not write the tens and the ones next to each other. Add them to make one number.
Method. Start with the tens. Then add the ones.
- Start with the tens. One ten is 10 counters.1 ten = 10
- Add the ones. Count the ones on after the tens.10 + 7 = 17
- Write the answer. 17
Check. 1 ten and 7 ones is 17. ✓
Watch out. Do not write the tens and the ones next to each other. Add them to make one number.
Method. Start with the tens. Then add the ones.
- Start with the tens. One ten is 10 counters.1 ten = 10
- Add the ones. Count the ones on after the tens.10 + 0 = 10
- Write the answer. 10
Check. 1 ten and 0 ones is 10. ✓
Watch out. Do not write the tens and the ones next to each other. Add them to make one number.
Method. Find the full ten first. What is left over is the ones.
- Find the full ten frame. A full ten frame has 10 counters.10 counters
- Take the ten away from the counters. What is left over is the ones.15 − 10 = 5
- Write the number of ones. Count the counters that are not in the full ten.5
Check. Ten and 5 more make 15: 10 + 5 = 15. ✓
Watch out. Take away the full ten first, then count what is left.
Method. Count the full tens first. Then count the ones that are left.
- Count the tens. A ten is ten counters, or one full ten frame.1 ten = 10
- Count the ones. The ones are the counters that are left over.9 ones
- Write it with tens and ones. Say the tens first, then the ones.1 ten and 9 ones
Check. 10 + 9 = 19, so 19 is 1 ten and 9 ones. ✓
Watch out. Say the tens first, then the ones. One ten is 10, not 1.
Method. Count the full tens first. Then count the ones that are left.
- Count the tens. A ten is ten counters, or one full ten frame.1 ten = 10
- Count the ones. The ones are the counters that are left over.4 ones
- Write it with tens and ones. Say the tens first, then the ones.1 ten and 4 ones
Check. 10 + 4 = 14, so 14 is 1 ten and 4 ones. ✓
Watch out. Say the tens first, then the ones. One ten is 10, not 1.
Method. Count on from 18 until you reach 20. Count how many steps you took.
- Start with 18 counters. These counters are already on the ten frames.18 counters
- Add counters until there are 20. Fill the empty spaces on the ten frames.18 + 2 = 20
- Write how many more. The number you added is the answer.2
Check. 18 + 2 = 20. ✓
Watch out. Look for the empty spaces on the ten frames. Count only those.
Method. Count the full ten first, then count the ones that are left over.
- Find the full ten frame. A full ten frame has 10 counters. Start with ten, not with one.10 counters in the full tens
- Count the ones left over. These are the counters outside the full ten.7 ones
- Add them together. Ten and some more make a teen number.10 + 7 = 17
- Write the answer. 17
Check. Count all 17 counters one at a time. You get 17 again. ✓
Watch out. Start with ten, not with one. Then count on the ones.
Method. Check how many tens and how many ones are in 15, then compare with what Sam said.
- Look at the number 15. Ten and some more make 15.15 = 10 + 5
- Count the tens and ones. One full ten and 5 ones make 15.1 ten and 5 ones
- Compare with Sam. Sam said 5 tens. That would be 50, not 15.5 tens is not 15
Check. 10 + 5 = 15, so 15 is 1 ten and 5 ones. ✓
Watch out. The 1 in 15 means one ten. It does not mean five tens.
Method. Count the full ten first, then count the ones that are left over.
- Find the full ten frame. A full ten frame has 10 counters. Start with ten, not with one.10 counters in the full tens
- Count the ones left over. These are the counters outside the full ten.6 ones
- Add them together. Ten and some more make a teen number.10 + 6 = 16
- Write the answer. 16
Check. Count all 16 counters one at a time. You get 16 again. ✓
Watch out. Start with ten, not with one. Then count on the ones.
One more, one less and the number line to 20
Printable: Worksheet (PDF) · Answers (PDF) · Open this lesson on its own page
The number line goes from 0 on the left to 20 on the right. Each number is one step further right than the number before it.
One more is the next number, one step to the right. One less is the number just before, one step to the left.
The same rule works past ten. One more than 19 is 20. One less than 11 is 10.
Key ideas
- One more is the next number on the right.
- One less is the number before, on the left.
- One more than 19 is 20.
- Use the number line, or ten frames, to check.
Key words. One more is the next number. One less is the number just before.
Method. Start at 15. One more is the number after 15.
- Start at 15. Put your finger on the number.Start: 15
- Move one step forward. Each step on the number line is one number.15 + 1 = 16
- Write the answer. 16
Check. Check it: 16 − 1 = 15. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Key words. One more is the next number. One less is the number just before.
Method. Start at 20. One less is the number before 20.
- Start at 20. Put your finger on the number.Start: 20
- Move one step back. Each step on the number line is one number.20 − 1 = 19
- Write the answer. 19
Check. Check it: 19 + 1 = 20. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Method. Each number is one more than the number before it. Use the numbers you can see to find the gaps.
- Look at the numbers before each gap. Counting on in ones means each number is one more than the one before.16, 17, ?, 19
- Count on one from the number before each gap. Add 1 to the number before the gap.Gap 3: 17 + 1 = 18
- Write the missing numbers. 18
Check. Read the whole line again: each number is one more than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go up by one.
Watch out
Watch out: one more than 19 is 20. Do not write the digits 1 and 9 again, and do not write 19 again. Write the next number.
Exam tip
Grown-up tip. Draw a number line from 0 to 20 on paper. Put a finger on a number. Say “one more” and move one step right. Then say “one less” and move one step left.
Exercise 4D One more, one less and moving along
Non-calculatorKey words. One more is the next number. One less is the number just before.
Method. Start at 12. One more is the number after 12.
- Start at 12. Put your finger on the number.Start: 12
- Move one step forward. Each step on the number line is one number.12 + 1 = 13
- Write the answer. 13
Check. Check it: 13 − 1 = 12. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Key words. One more is the next number. One less is the number just before.
Method. Start at 16. One more is the number after 16.
- Start at 16. Put your finger on the number.Start: 16
- Move one step forward. Each step on the number line is one number.16 + 1 = 17
- Write the answer. 17
Check. Check it: 17 − 1 = 16. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Key words. One more is the next number. One less is the number just before.
Method. Start at 19. One more is the number after 19.
- Start at 19. Put your finger on the number.Start: 19
- Move one step forward. Each step on the number line is one number.19 + 1 = 20
- Write the answer. 20
Check. Check it: 20 − 1 = 19. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Key words. One more is the next number. One less is the number just before.
Method. Start at 14. One less is the number before 14.
- Start at 14. Put your finger on the number.Start: 14
- Move one step back. Each step on the number line is one number.14 − 1 = 13
- Write the answer. 13
Check. Check it: 13 + 1 = 14. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Key words. One more is the next number. One less is the number just before.
Method. Start at 20. One less is the number before 20.
- Start at 20. Put your finger on the number.Start: 20
- Move one step back. Each step on the number line is one number.20 − 1 = 19
- Write the answer. 19
Check. Check it: 19 + 1 = 20. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Key words. One more is the next number. One less is the number just before.
Method. Start at 11. One less is the number before 11.
- Start at 11. Put your finger on the number.Start: 11
- Move one step back. Each step on the number line is one number.11 − 1 = 10
- Write the answer. 10
Check. Check it: 10 + 1 = 11. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Key words. One more is the next number. One less is the number just before.
Method. Start at 9. One more is the number after 9.
- Start at 9. Put your finger on the number.Start: 9
- Move one step forward. Each step on the number line is one number.9 + 1 = 10
- Write the answer. 10
Check. Check it: 10 − 1 = 9. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Key words. One more is the next number. One less is the number just before.
Method. Start at 10. One less is the number before 10.
- Start at 10. Put your finger on the number.Start: 10
- Move one step back. Each step on the number line is one number.10 − 1 = 9
- Write the answer. 9
Check. Check it: 9 + 1 = 10. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Method. Each number is one more than the number before it. Use the numbers you can see to find the gaps.
- Look at the numbers before each gap. Counting on in ones means each number is one more than the one before.0, 1, 2, 3, 4, 5, 6, ?, 8, 9, 10, 11, 12, 13, 14, ?, 16, 17, 18, 19, 20
- Count on one from the number before each gap. Add 1 to the number before the gap.Gap 8: 6 + 1 = 7
Gap 16: 14 + 1 = 15 - Write the missing numbers. 7, 15
Check. Read the whole line again: each number is one more than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go up by one.
Method. Start at 13. Move one step at a time, forwards.
- Start at 13. Put your finger on the start number.13
- Move 1 step forward. Say each number as you land on it.13, 14
- Write where you end up. The last number is where you finish.14
Check. Count the steps again: you took 1 step. ✓
Watch out. Count the steps, not the numbers. The start number is not a step.
Method. Start at 18. Move one step at a time, backwards.
- Start at 18. Put your finger on the start number.18
- Move 2 steps backwards. Say each number as you land on it.18, 17, 16
- Write where you end up. The last number is where you finish.16
Check. Count the steps again: you took 2 steps. ✓
Watch out. Count the steps, not the numbers. The start number is not a step.
Method. Start at 5. Move one step at a time, forwards.
- Start at 5. Put your finger on the start number.5
- Move 3 steps forwards. Say each number as you land on it.5, 6, 7, 8
- Write where you end up. The last number is where you finish.8
Check. Count the steps again: you took 3 steps. ✓
Watch out. Count the steps, not the numbers. The start number is not a step.
Key words. One more is the next number. One less is the number just before.
Method. Start at 14. One more is the number after 14.
- Start at 14. Put your finger on the number.Start: 14
- Move one step forward. Each step on the number line is one number.14 + 1 = 15
- Write the answer. 15
Check. Check it: 15 − 1 = 14. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Key words. One more is the next number. One less is the number just before.
Method. Start at 17. One less is the number before 17.
- Start at 17. Put your finger on the number.Start: 17
- Move one step back. Each step on the number line is one number.17 − 1 = 16
- Write the answer. 16
Check. Check it: 16 + 1 = 17. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Key words. One more is the next number. One less is the number just before.
Method. Start at 20. One less is the number before 20.
- Start at 20. Put your finger on the number.Start: 20
- Move one step back. Each step on the number line is one number.20 − 1 = 19
- Write the answer. 19
Check. Check it: 19 + 1 = 20. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Method. Count on one from 19 on the number line. The next number is 20.
- Start at 19. Find 19 on the number line.19
- Move one step right. One more is the next number on the right.19 + 1 = 20
- Compare with Ben’s answer. The next number is 20, not 91. The digits 9 and 1 do not come next.20
Check. Count on from 19: the next number is 20. ✓
Watch out. One more adds one. It does not join the digits together.
Method. Each number is one more than the number before it. Use the numbers you can see to find the gaps.
- Look at the numbers before each gap. Counting on in ones means each number is one more than the one before.17, 18, 19, ?, 21
- Count on one from the number before each gap. Add 1 to the number before the gap.Gap 4: 19 + 1 = 20
- Write the missing numbers. 20
Check. Read the whole line again: each number is one more than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go up by one.
Comparing and ordering numbers to 20
Printable: Worksheet (PDF) · Answers (PDF) · Open this lesson on its own page
On a number line, the bigger number is further to the right. The smaller number is further to the left.
A number from eleven to twenty is always bigger than any number from one to nine. Fifteen is ten and five more, so it is bigger than nine.
We can put numbers in order, smallest first or biggest first. The number between two numbers sits in the middle of them.
Key ideas
- Bigger numbers are further to the right.
- Any number from 11 to 20 is bigger than any number from 1 to 9.
- Order means smallest first, or biggest first.
- The number between two numbers is in the middle of them.
Method. The biggest number is the one furthest to the right on the number line.
- Find each number on the number line. Look at where each one sits.
- Find the biggest number. Bigger numbers are further right.14 is the biggest number.
- Write the answer. 14
Check. Compare 14 with each of the others: 14 > each one. ✓
Watch out. Do not look at the size of the writing. Compare the numbers.
Key words. Smallest is the least. Biggest is the most.
Method. Smallest first. Look at where each number sits on the number line.
- Find each number on the number line. Numbers further to the left are smaller.
- Put the numbers in order. Start with the smallest and go to the next one.11, 12, 15, 18
- Write the numbers. 11, 12, 15, 18
Check. There are 4 numbers in the question and 4 in the answer. ✓
Watch out. Check you have not left a number out.
Key words. Between means in the middle of two numbers.
Method. The number between 16 and 18 sits in the middle of them.
- Find 16 and 18 on the number line. Put your finger on each one.
- Count on one from the smaller number. The number in the middle is one more than the smaller one.16 + 1 = 17
- Write the answer. 17
Check. Count on from 17 to 18: 17 + 1 = 18. ✓
Watch out. The number between is not one of the two numbers you started with.
Watch out
Watch out: 12 has two digits and 9 has one digit, and 12 is the bigger number. Do not guess from the digits. Look at the number line.
Exam tip
Grown-up tip. Write five numbers from 1 to 20 on cards and mix them up. Ask your child to put them in order, smallest first. Then ask: “Which number is between 13 and 15?”
Exercise 4E Comparing, ordering and between
Non-calculatorMethod. The biggest number is the one furthest to the right on the number line.
- Find each number on the number line. Look at where each one sits.
- Find the biggest number. Bigger numbers are further right.19 is the biggest number.
- Write the answer. 19
Check. Compare 19 with each of the others: 19 > each one. ✓
Watch out. Do not look at the size of the writing. Compare the numbers.
Method. The smallest number is the one furthest to the left on the number line.
- Find each number on the number line. Look at where each one sits.
- Find the smallest number. Smaller numbers are further left.16 is the smallest number.
- Write the answer. 16
Check. Compare 16 with each of the others: 16 < each one. ✓
Watch out. Do not look at the size of the writing. Compare the numbers.
Method. The biggest number is the one furthest to the right on the number line.
- Find each number on the number line. Look at where each one sits.
- Find the biggest number. Bigger numbers are further right.12 is the biggest number.
- Write the answer. 12
Check. Compare 12 with each of the others: 12 > each one. ✓
Watch out. Do not look at the size of the writing. Compare the numbers.
Key words. Smallest is the least. Biggest is the most.
Method. Smallest first. Look at where each number sits on the number line.
- Find each number on the number line. Numbers further to the left are smaller.
- Put the numbers in order. Start with the smallest and go to the next one.11, 14, 17
- Write the numbers. 11, 14, 17
Check. There are 3 numbers in the question and 3 in the answer. ✓
Watch out. Check you have not left a number out.
Key words. Smallest is the least. Biggest is the most.
Method. Biggest first. Look at where each number sits on the number line.
- Find each number on the number line. Numbers further to the left are smaller.
- Put the numbers in order. Start with the biggest and go to the next one.20, 13, 9
- Write the numbers. 20, 13, 9
Check. There are 3 numbers in the question and 3 in the answer. ✓
Watch out. Check you have not left a number out.
Key words. Between means in the middle of two numbers.
Method. The number between 12 and 14 sits in the middle of them.
- Find 12 and 14 on the number line. Put your finger on each one.
- Count on one from the smaller number. The number in the middle is one more than the smaller one.12 + 1 = 13
- Write the answer. 13
Check. Count on from 13 to 14: 13 + 1 = 14. ✓
Watch out. The number between is not one of the two numbers you started with.
Key words. Between means in the middle of two numbers.
Method. The number between 18 and 20 sits in the middle of them.
- Find 18 and 20 on the number line. Put your finger on each one.
- Count on one from the smaller number. The number in the middle is one more than the smaller one.18 + 1 = 19
- Write the answer. 19
Check. Count on from 19 to 20: 19 + 1 = 20. ✓
Watch out. The number between is not one of the two numbers you started with.
Key words. More means a bigger number. Fewer means a smaller number. The same means equal.
Method. Count each group, then see which number is bigger.
- Count group A. Touch each one once.Group A: 14 apples
- Count group B. Touch each one once.Group B: 11 stars
- Compare the two numbers. The bigger number has more. The smaller number has fewer.14 > 11
- Write the answer. Group A has more apples.
Check. Match one to one: each thing in one group gets a partner from the other. The group with a thing left over has more. ✓
Watch out. Groups can look bigger when the things are spread out. Always count them.
Key words. More means a bigger number. Fewer means a smaller number. The same means equal.
Method. Count each group, then see which number is smaller.
- Count group A. Touch each one once.Group A: 16 cubes
- Count group B. Touch each one once.Group B: 19 balls
- Compare the two numbers. The bigger number has more. The smaller number has fewer.16 < 19
- Write the answer. Group A has fewer cubes.
Check. Match one to one: each thing in one group gets a partner from the other. The group with a thing left over has more. ✓
Watch out. Groups can look bigger when the things are spread out. Always count them.
Method. Count each person’s things, then compare the two numbers.
- Count what Sam has. Touch each one once.Sam: 13
- Count what Priya has. Touch each one once.Priya: 18
- Compare the two numbers. The bigger number is more.18 is bigger than 13
- Write the answer. Priya has more.
Check. The bigger number is further to the right on the number line. ✓
Watch out. Compare the numbers, not the names.
Key words. Smallest is the least. Biggest is the most.
Method. Smallest first. Look at where each number sits on the number line.
- Find each number on the number line. Numbers further to the left are smaller.
- Put the numbers in order. Start with the smallest and go to the next one.5, 10, 15, 20
- Write the numbers. 5, 10, 15, 20
Check. There are 4 numbers in the question and 4 in the answer. ✓
Watch out. Check you have not left a number out.
Key words. Between means in the middle of two numbers.
Method. The number between 14 and 16 sits in the middle of them.
- Find 14 and 16 on the number line. Put your finger on each one.
- Count on one from the smaller number. The number in the middle is one more than the smaller one.14 + 1 = 15
- Write the answer. 15
Check. Count on from 15 to 16: 15 + 1 = 16. ✓
Watch out. The number between is not one of the two numbers you started with.
Method. Compare 9 and 15 on the number line. The number further to the right is bigger.
- Find 9 and 15 on the number line. Look at where each one sits.9 and 15
- Compare the two numbers. 15 is ten and five more. That is more than 9.15 is bigger than 9
- Write the answer. No. 15 is bigger than 9, because 15 is 10 and 5 more.
Check. Count on from 9 to 15. You pass the 10. ✓
Watch out. A short word does not mean a small number. Compare the numbers.
Key words. Smallest is the least. Biggest is the most.
Method. Biggest first. Look at where each number sits on the number line.
- Find each number on the number line. Numbers further to the left are smaller.
- Put the numbers in order. Start with the biggest and go to the next one.19, 13, 11
- Write the numbers. 19, 13, 11
Check. There are 3 numbers in the question and 3 in the answer. ✓
Watch out. Check you have not left a number out.
Chapter summary
| Skill | Method |
|---|---|
| Count to 20 | Say one number for each thing, in order. Count on past ten, and start a new ten. |
| Numerals and words | Eleven and twelve have their own names. Thirteen to nineteen end in teen. Twenty comes after nineteen. |
| Tens and ones | A full ten frame is one ten. The counters left over are the ones. 13 is 1 ten and 3 ones. |
| One more and one less | One more is the next number on the right. One less is the number just before, on the left. |
| Compare and order | Bigger numbers are further right on the number line. Any number from 11 to 20 is bigger than 1 to 9. |
| Between | The number in the middle of two numbers, for example 17 is between 16 and 18. |
Can you…?
- I can count forwards and backwards to 20
- I can read and write the numbers 11 to 20 as numerals and as words
- I can say how many tens and ones are in a number to 20, using a ten frame
- I can say the number that is one more or one less, up to 20
- I can count on and back along a number line to 20
- I can say which of two numbers to 20 is bigger, and put them in order
Key terms
- count on
- keep going up from a number, one at a time
- count back
- go down from a number, one at a time
- numeral
- a number written with digits, like 14
- number word
- the name of a number, like fourteen
- teen number
- a number from 13 to 19: ten and some more
- ten frame
- a box with two rows of five spaces for counters
- tens and ones
- a number split into full tens and the ones left over
- one more
- the next number
- one less
- the number just before
- number line
- a line with numbers in order, smallest on the left
- between
- in the middle of two numbers
Exercise 4Z Check-up
Non-calculatorKey words. To count is to say one number for each thing, in order: 1, 2, 3, and so on.
Method. Say one number for each one, and touch each one only once. The last number you say is how many there are.
- Count each one and say its number. Each one gets one number. Do not miss one and do not count one twice.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
- Look at the last number you said. The last number tells us how many there are altogether.The last number is 15.
- Write the answer. There are 15 apples.
Check. Count again from the other side. You get 15 again. ✓
Watch out. Move each one to one side as you count it, so you do not lose your place.
Method. Read the number word, then find it on the number list.
- Read the word. Read the whole word, not just the first letters.“thirteen”
- Find the word on the number list. Each word matches exactly one number.thirteen = 13
- Write the numeral. A numeral is the number written with digits.13
Check. Count 13 things. The last number you say is 13. ✓
Watch out. Teen numbers end in teen. Check every letter of thirteen.
Key words. A numeral is a number written with digits, like 14. A number word is its name, like fourteen.
Method. Say the number out loud, then write its name in words.
- Say the number. Listen to how it sounds.18
- Find its name on the number list. Every number has one name.18 = eighteen
- Write the word, one letter at a time. The word has 8 letters.eighteen
Check. Count out 18 things and say “eighteen” at the end. ✓
Watch out. Teen numbers end in teen. Check every letter of eighteen.
Key words. One more is the next number. One less is the number just before.
Method. Start at 12. One more is the number after 12.
- Start at 12. Put your finger on the number.Start: 12
- Move one step forward. Each step on the number line is one number.12 + 1 = 13
- Write the answer. 13
Check. Check it: 13 − 1 = 12. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Key words. One more is the next number. One less is the number just before.
Method. Start at 16. One less is the number before 16.
- Start at 16. Put your finger on the number.Start: 16
- Move one step back. Each step on the number line is one number.16 − 1 = 15
- Write the answer. 15
Check. Check it: 15 + 1 = 16. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Key words. More means a bigger number. Fewer means a smaller number. The same means equal.
Method. Count each group, then see which number is bigger.
- Count group A. Touch each one once.Group A: 12 stars
- Count group B. Touch each one once.Group B: 17 apples
- Compare the two numbers. The bigger number has more. The smaller number has fewer.12 < 17
- Write the answer. Group B has more apples.
Check. Match one to one: each thing in one group gets a partner from the other. The group with a thing left over has more. ✓
Watch out. Groups can look bigger when the things are spread out. Always count them.
Key words. Smallest is the least. Biggest is the most.
Method. Smallest first. Look at where each number sits on the number line.
- Find each number on the number line. Numbers further to the left are smaller.
- Put the numbers in order. Start with the smallest and go to the next one.8, 11, 14, 19
- Write the numbers. 8, 11, 14, 19
Check. There are 4 numbers in the question and 4 in the answer. ✓
Watch out. Check you have not left a number out.
Key words. Between means in the middle of two numbers.
Method. The number between 15 and 17 sits in the middle of them.
- Find 15 and 17 on the number line. Put your finger on each one.
- Count on one from the smaller number. The number in the middle is one more than the smaller one.15 + 1 = 16
- Write the answer. 16
Check. Count on from 16 to 17: 16 + 1 = 17. ✓
Watch out. The number between is not one of the two numbers you started with.
Method. Count the full tens first. Then count the ones that are left.
- Count the tens. A ten is ten counters, or one full ten frame.1 ten = 10
- Count the ones. The ones are the counters that are left over.7 ones
- Write it with tens and ones. Say the tens first, then the ones.1 ten and 7 ones
Check. 10 + 7 = 17, so 17 is 1 ten and 7 ones. ✓
Watch out. Say the tens first, then the ones. One ten is 10, not 1.
Method. Count back from 20 to 17. Each number is one less than the number before it.
- Start at the first number. We start with the biggest number.20
- Take away one each time. Each number is one less than the one before.20, 19, 18, 17
- Write the numbers. Include the start number and the end number.20, 19, 18, 17
Check. Count on from 17 to 20 to check. ✓
Watch out. Count back in the same way each time. Do not skip a number, and do not say a number twice.
Total 15 marks. Allow about 15 minutes.
Exercise 4X End-of-chapter quiz
Non-calculatorKey words. One more is the next number. One less is the number just before.
Method. Start at 19. One more is the number after 19.
- Start at 19. Put your finger on the number.Start: 19
- Move one step forward. Each step on the number line is one number.19 + 1 = 20
- Write the answer. 20
Check. Check it: 20 − 1 = 19. ✓
Watch out. Move one step, not two. Do not write the number you started with.
Method. Read the number word, then find it on the number list.
- Read the word. Read the whole word, not just the first letters.“twelve”
- Find the word on the number list. Each word matches exactly one number.twelve = 12
- Write the numeral. A numeral is the number written with digits.12
Check. Count 12 things. The last number you say is 12. ✓
Watch out. twelve does not end in teen. Learn it as its own name.
Key words. To count is to say one number for each thing, in order: 1, 2, 3, and so on.
Method. Say one number for each one, and touch each one only once. The last number you say is how many there are.
- Count each one and say its number. Each one gets one number. Do not miss one and do not count one twice.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14
- Look at the last number you said. The last number tells us how many there are altogether.The last number is 14.
- Write the answer. There are 14 stars.
Check. Count again from the other side. You get 14 again. ✓
Watch out. Move each one to one side as you count it, so you do not lose your place.
Method. Start with the tens. Then add the ones.
- Start with the tens. One ten is 10 counters.1 ten = 10
- Add the ones. Count the ones on after the tens.10 + 6 = 16
- Write the answer. 16
Check. 1 ten and 6 ones is 16. ✓
Watch out. Do not write the tens and the ones next to each other. Add them to make one number.
Key words. More means a bigger number. Fewer means a smaller number. The same means equal.
Method. Count each group, then see which number is smaller.
- Count group A. Touch each one once.Group A: 18 balls
- Count group B. Touch each one once.Group B: 13 cubes
- Compare the two numbers. The bigger number has more. The smaller number has fewer.18 > 13
- Write the answer. Group B has fewer cubes.
Check. Match one to one: each thing in one group gets a partner from the other. The group with a thing left over has more. ✓
Watch out. Groups can look bigger when the things are spread out. Always count them.
Key words. Smallest is the least. Biggest is the most.
Method. Smallest first. Look at where each number sits on the number line.
- Find each number on the number line. Numbers further to the left are smaller.
- Put the numbers in order. Start with the smallest and go to the next one.4, 9, 16, 20
- Write the numbers. 4, 9, 16, 20
Check. There are 4 numbers in the question and 4 in the answer. ✓
Watch out. Check you have not left a number out.
Method. Start at 17. Count on one number at a time until you reach 20.
- Start at 17. That is the first number you say.17
- Count on one at a time to 20. Each number is one more than the number before it.17, 18, 19, 20
- Write the numbers. Include the first number and the last number.17, 18, 19, 20
Check. Count back from 20 to 17 to check. ✓
Watch out. Do not skip a number when you go past ten. After nine comes ten, then eleven.
Method. Each number is one more than the number before it. Use the numbers you can see to find the gaps.
- Look at the numbers before each gap. Counting on in ones means each number is one more than the one before.15, ?, 17, ?, 19
- Count on one from the number before each gap. Add 1 to the number before the gap.Gap 2: 15 + 1 = 16
Gap 4: 17 + 1 = 18 - Write the missing numbers. 16, 18
Check. Read the whole line again: each number is one more than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go up by one.
Method. Count the full tens first. Then count the ones that are left.
- Count the tens. A ten is ten counters, or one full ten frame.1 ten = 10
- Count the ones. The ones are the counters that are left over.6 ones
- Write it with tens and ones. Say the tens first, then the ones.1 ten and 6 ones
Check. 10 + 6 = 16, so 16 is 1 ten and 6 ones. ✓
Watch out. Say the tens first, then the ones. One ten is 10, not 1.
Method. Check Aisha’s idea by counting on from 19.
- Count on from 19. One more than 19 is the next number.19, 20
- Look at what Aisha said. Aisha said 20 comes before 19. But 19 comes before 20.19 comes before 20
- Write the answer. No. 19 comes before 20, so 20 comes after 19.
Check. On the number line, 20 is one step right of 19. ✓
Watch out. The number that comes after is the bigger number.