## Subtraction Using the Counting Back Strategy

I am learning to use the counting back strategy to solve subtraction problems.

I know I can do it when I am counting back from the biggest number in a subtraction problem.

This week we are looking at solving subtraction problems, focusing on counting back from the largest number. Learning to do this allows us to subtract from a collection of objects much quicker.

To complete today’s task, you will need some playing cards or two dice. If you don’t have any, follow this link for some online dice.

Using cards:

• Remove all of the picture cards and the 10s from your deck so that you only have Aces through to 9s.
• Choose two cards from your deck (eg. 3, 4).
• starting from the biggest number, use the counting back strategy to work out what you would have left if you subtracted the smallest number from the largest number (4-3=1).
• On a piece of paper, write down the subtraction problem that you have solved.

Using dice:

• Roll two dice (10 sided if you have them)
• starting from the biggest number, use the counting back strategy to work out what you would have left if you subtracted the smaller number on the dice from the largest number on the dice (4-3=1).
• On a piece of paper, write down the subtraction problem that you have solved.

Repeat this process at least 5 times.

If you wish to challenge yourself, you could try to use mental strategies to subtract 2-digit numbers.

## Counting Backwards From a Non-Zero Starting Point

I am learning to count backwards starting from ANY number.

I know I can do it when I am able to count backwards from a non-zero starting point.

Yesterday we practised count forwards from numbers other than zero, today we are going to practise counting backwards.

You may wish to use the 100s chart that you used yesterday.

The online version can be found here.

Like yesterday, you will be using playing cards or dice to find 2-digit numbers. If you do not have playing cards or dice, you can find some virtual dice here.

Remember – If you are using playing cards, you will need to remove the Jacks, Queens, Kings, Jokers and 10s.

Roll 2 dice or pick two playing cards from your deck to make a 2-digit number (for example 43). In your Maths book, write down the previous 8 numbers (for example 42, 41, 40, 39…).

Repeat this with at least 5 different numbers.

If you are finding this too tricky, try only using numbers less than 30.

If you want to challenge yourself, you could start with 3-digit or 4-digit numbers.

## Making 10

I am learning to use number facts to add up to 10.

I know I can do it when I can add numbers to make 10.

Today you will be using the ‘Friends of Ten’ to add numbers up to 10. Watch the song below to learn more about the Friends of Ten. ↓↓↓

For today’s activity, you will need a deck of playing cards.

How to play:

First you will need to remove all of the picture cards (King, Queen, Jack and Joker), you will also need to remove the 10s.

To start, lay out 7 playing cards in a line face up to see the numbers. (see example below) ↓↓↓

Remove any pairs of cards that add together to make 10. Move those to the side and replace the missing cards with others from the deck. (see picture below) ↓↓↓

Continue removing any pairs that add together to make 10. If you can’t find any pairs from the 7 cards, replace them with another 7.

Keep playing until you can’t make anymore pairs.

### Extension

If you want to challenge yourself, put the picture cards and the 10s back into the deck.

Jack = 11, Queen =12, King =13, Joker = 14.

Remove cards if they add up to 20 instead of 10. You can use more than 2 cards at a time.

For example: Jack + 5 + 4 = 20 OR 3 + 9 + 8 = 20 ↓↓↓