Year 3

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We know the sum and difference of any pair of numbers to 20.
We can add and subtract multiples of 10 or 100 in our head.

Year 3 Unit 3

What we are learning:

  • Addition and Subtraction facts are often referred to in schools as ‘number bonds’. Number bonds to 10 are the pairs of numbers that add to make 10 (or another number) i.e. 0+10, 1+9, 2+8 … and the partner subtractions 10-10=0, 10-9=1, 10-8=2.
  • It is important for your child to know the number bonds for all numbers to 20.
  • Fingers are really good for practicing number bonds to 5 and 10!
  • An empty egg box with bricks/ small cars/hair slides etc in is really good for practising number bonds to 6 (or 12!).
  • The more your child practises the different number bonds the quicker they will become. 5 minutes practice every day will make a big difference.
  • ‘Sum’ is a different (mathematical) way of saying ‘the total found by adding’.
  • ‘Difference’ is a different (mathematical) way of saying ‘the value between the two numbers’ which is found by subtracting the lower value from the higher value.
  • Multiples of 10 have 0 units. 10, 20, 30, 40 ….
  • Multiples of 100 have 0 tens and 0 units. 100, 200, 300, 400 …
  • Mathematicians sometimes refer to the pairs of numbers that total 100 as the complements to 100 (50 and 50, 32 and 68, 94 and 6 etc)

Activities you can do at home:

Write down a number between 5 and 20 in the middle of a sheet of paper. Draw a circle round it. Give your child a few minutes (vary the time given according to the number you choose and how confident they are) to write down all of the number bonds (addition and subtraction) for this number. Doing this regularly will speed up their recall of key facts.

Use the sheet “Number bonds”. Cut out the calculation cards. Place the addition facts to 10 (in order) in a horizontal line. 0+10 =10, 1+9 = 10, 2+8 = 10, 3+7 =10, 4+6=10, 5+5=10, 6+4=10, 7+3=10, 8+2=10, 9+1=10, 10+0=10.
Now place the corresponding addition facts to 100 underneath.
Look at the patterns with your child and talk about the similarities they can see.

Make a pile of 10p coins – you will need at least £2 worth. Verbally give your child a calculation to do using the 10p coins. Start with 10. Your child takes a 10p and places this in front of him.
Add 30 Your child takes three 10ps and adds this to the pile.
How many do you have now? Your child answers “40”
Add 50 Your child takes five 10ps and adds this to the pile.
How many do you have now? Your child answers “90”
Take away 20 Your child takes away two 10ps.
How many do you have now? Your child answers “70”.
This game should be played for about 5 minutes – encourage your child to keep telling you the running total so that there is no need for you to prompt with How many do you have now?

Good questions to ask:

What do we mean by ‘find the sum of’?
What is another word for subtraction?
How many different ways can we make the number…..using addition / subtraction?
If 3 + 4 is 7 what is 30 + 40?
What is 300 + 400?

If your child:

Knows the number bonds to 20 well
The application of this beyond 20, e.g.
What is 12 + 8?
What is 22 + 8?
What is 32 + 8?
What is 20 – 17
What is 30 – 17?
What is 40 – 17?

Extension Activity

Please use this activity when you think your child understands the unit of work. It will deepen and extend your child’s understanding of this unit.


Extension activity (PDF)