Unit 2: Problem
Solving
with
Mrs.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
4x3x5
How would you work this one out?
15 x 3 x 2
And this one?
2x3x4x5
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
19 x 8
17 x 4
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 4
Chips 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
fish £2
chips £1
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.
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+7x3
4+7+3
4x2x3
4–2x3
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.