Year 2

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We can add and subtract two-digit numbers using practical equipment.
We can add and subtract in our head.

Year 2 Unit 16a

What we are learning:

  • Addition can be done in any order. The order chosen should reflect the numbers in the addition:
    20 + 8 = start with the 20 (biggest number) and add on 8
    6 + 30 = start with 30 (biggest number) and add on 6
    7 + 20 + 3 = add the 7 and 3 first to make 10, then add to the 20
    Always look for the simplest order to add the numbers together.
  • Subtraction cannot be done in any order. The method used for mental subtraction should be chosen to reflect the numbers in the subtraction:
    20 – 7 = start on 20 and count back 7 (we are not taking many away)
    26 – 21 = start on 21 and count on until we get to 26 (your child should be able to see that the difference between the numbers is small). You can use a number line to show this.

Activities you can do at home:

Activity 1 Addition and subtraction games
Make two sets of number cards of two-digit numbers including the multiples of ten, and one digit numbers and some operation cards addition and subtraction( -, +). Shuffle the cards and place face down in three different piles (two-digit numbers, one-digit numbers and the operation cards).

Take a card from each pile. For example 7 + 20. Add these together mentally, or using resources or on a number line. Don’t forget to re-order the numbers – so for the question above the child should put the larger number first and add on the smaller number.
Remember if you use objects to help you just need to count out the 7 and count on from 20.

Good questions to ask

What is 20 + 8?
How did you work it out in your head?
What is 5 + 20+5? How did you work it out? Are there any other ways of working this out? Which is the easiest way for you?

If your child:

Chooses an addition order that means they have to count on a large amount, e.g. 4 + 15 rather than 15 + 4
Let them do the calculation the long way they have chosen. When they have completed it ask them if there is another way of doing it and explore the difference. It is only by comparing their experience that they will look for
shorter, easier methods in the future.

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)