Unit 2: Problem Solving

withMrs.Campbell

Our objective today is:

• Identify factor pairs of small two-digit numbers

• Use factors as a strategy for mental multiplication.

Identify factor pairs

36

What do we call 36?

6x6=36

What are the factors of:

40 24 64

Use factors as a strategy for mental multiplication

4 x 3 x 5

How would you work this one out?

15 x 3 x 2

And this one?

2 x 3 x 4 x 5

Ooh, what about this?

17 X 12

Let’s look at this problem lots of ways

17 X 12

17 X 6 X 2

17 x 3 x 2 x 2 = 51 x 2 x 2 =

102 x 2 = 204.

Can you use this method to work out the following?

23 x 6 17 x 4

19 x 8

Now try these..

Day 2

• Order a set of positive and negative integers.

• Solve simple word problems.

• Begin to use brackets.

-20 0 +20

-20 0 +20

I have just spent £9. What could I have bought?

fish £2 chips £1

Fish 0 1 2 3 4Chips 9 7 5 3 1

Say a cola cost 50p and pizza £1.50. If I spend £8 what can I buy?

• In your pairs I want you to create a similar problem for other pairs to answer. You can have 10 minutes to sort something out

• We will discuss the problems and solutions.

Can you work out this puzzle

A man goes to the chip shop, and asks for “two fish and chips”. The owner asks for £6, but the man expects the total to be £5.

fish £2 chips £1

Is it ‘two (fish and chips)’

or ‘(two fish) and chips’

•2 x (£2 + £1)

• (2 x £2) + £1.

How would you work out this calculation?

6 + 3 – 2 6 – 3 + 2

What is the answer to these?

• (6 + 3) – 2 6 + (3 – 2 )

What is the answer to these?• (6 – 3) + 2 6 – (3 + 2).

How is the answer changed?

Give me a number between 20 and 50

• Roll a dice 3 times and record the numbers.

• Work with your partner to make a calculation using the 3 numbers and brackets to try and reach the target number

Here is my one!

30 is my target number I rolled the dice 3 times and got a 6,1 and a 4. These are my

calculations: (6 – 1) x 4 (6 x 4) + 1 6 x (4 + 1) (6 + 1) x 4.

Reflect

Now think about what we have been learning about.

Can you apply your learning to these questions?

Where could I place the brackets to make the largest number?

4 + 7 x 34 + 7 + 34 x 2 x 34 – 2 x 3

What about the smallest number?

Teacher Notes

• This slide show is intended to be used in close conjunction with the notes. I suggest you print off the notes and familiarise yourself with them before the lesson. Use the notes to guide you through the slides.

• Additional problems will be needed for slide 12. Add as appropriate for your children.