Year 1

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We can add a multiple of 10 (20,30,40 etc) to a one-digit number.

Year 1 Unit 13

What we are learning:

We are now linking the concepts of adding and using multiples of 10 (using practical equipment)

At some stages when children are adding they will want to count from 1 and count both numbers. This is fine if it is what they need to do. In time you can ask, Do you always need to count the first number? or What happens if we start with this number and then count on? or Can you find another way of adding the numbers?


Activities you can do at home:

To add on a number line you can start at the first number and count on the required number of places for the second number. Talk together about which number is the best to start from.

Add three or more numbers together (rather than just two numbers) e.g. 10 + 10 + 5 + 3 =
Write the numbers on cards and change the order
Ask, What do you notice about the total?

Model asking mental addition questions adding a multiple of 10 to a onedigit number – so 20 + 4, 7 + 30, 8 + 20.
Model with apparatus – bundles of straws – bundles of 10 straws and single straws then moving to visualizing the straws even when they are no longer used.

How many bundles of ten straws do we need to make 20? 30? 40?

In my box I have 2 bundles of 10 straws and 6 single straws.
How many straws are in the box altogether? Check by counting.
Try this with different numbers
Ask your child to put straws in the box for you to count.
Turn over a number card and put than many straws in the box.
Look at the written number and the straws and talk about how each digit is represented by the straws

Good questions to ask:

How many are there altogether?
What is 10 more?
What is 10 less?
What is 20 more?

If your child:

Is confident using a number line or equipment
Ask them if they can count on and back in their head

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)