Transcript Y5T2U3D1_5 - Primary Resources

L.O.1
To be able to count in steps of equal size.
We are going to count in even time.
We’ll do 2’s, 20’s, 3’s, 30’s, 5’s, 50’s, and 0.5’s
L.O.2
To be able to use closely related facts:
multiplying by multiples of ten and
adjusting.
Mr. Buttons has 20 children in his class.
He orders reward stickers for the term.
He estimates that each child will earn 14
stickers – one each week. How many
stickers does he need to order?
Q. What calculation do we need to carry out to
answer this question?
The calculation is 14 x 20
Remember…..14 x 2 = 28
so
14 x 20 = 280
The 20 from the 28 has become 200 and the 8 has become 80.
so
14 x 20 = 280 stickers!
Q. How could we work out a similar
problem if there were 21 children in the
class?
Q. Should we start all over again or can
we use any information we already
have?
We can use the answer to 14 x 20 and
record :
14 x 21 = ( 14 x 20 ) + ( 14 x 1 )
= 280
+ 14
= 294 stickers.
Q. What if there were only 19 children
present?
Q. How could we use the information we
have to help us?
We could use the answer to 14 x 20 and
record:
14 x 19 = ( 14 x 20 ) – ( 14 x 1 )
=
280
14
=
266 stickers.
Do the sums from the accompanying
sheets in your book.
Set out your work properly and neatly.
=
X 41 is the same as
(
X 40 ) +
You are going to insert some numbers
in this equation and use calculators to
see if it is true.
Q. Do you think both calculations will always be the
same for any number you choose.
=
X 41
is the same as
(
X 40 ) +
With your partner write a word problem for
which the above would be a solution.
By the end of the lesson children should be
able to:
Understand how to calculate in multiples
of 10 and how to adjust for numbers close
to multiples of 10:
Multiply a number by 19 or 21, multiply it
by 20 and add or subtract the number.
L.O.1
To be able to count on in steps of equal
sizes
We are going to count in even time.
We’ll do 4’s, 5’s, 6’s, and 7’s
Q. How does counting in 4’s help us count in 8’s?
Q. How does counting in 3’s help us count in 6’s?
How does counting in 6’s help us count in 12’s?
How does counting in 7’s help us count in 14’s?
L.O.2
To be able to use closely related facts for
deriving multiplication and division facts
12 x 3 = 36
Q. Which number sentences can we derive from this one?
12 x 6 = 72
36 ÷ 12 = 3
120 x 3 = 360
36 ÷ 3 = 12
120 x 3 = 360
24 x 3 = 72
12 x 3 = 36
120 x 3 = 360
13 x 3 = 39
1.2 x 3 = 3.6
360 ÷ 30 = 12
With a partner draw a web map for this
number sentence.
Use a ruler!
Find as many associated facts as you can.
9 x 5 = 45
Now try these with a partner:
Prisms :
14 x 4, 16 x 5, 19 x 9, 23 x 7.
Spheres:
12 x 6, 14 x 7, 15 x 9.
Tetrahedra: 12 x 5, 13 x 8, 11 x 7.
When you have finished check other pairs’ work.
10 minutes
Now is the time to review the number strategies
we have used over the last two days.
11 x 4 = 44
What closely related facts can you tell me?
Q. Can you explain what you did to get the new
facts?
Write the following neatly in your books:
1. Adding and subtracting…
12 x 4 = 48, 11 x 4 = 44, 11 x 5 = 55
2. Making multiples of 10
11 x 40 = 440, 110 x 40 = 440, 110 x 40 = 4400.
3. Doubling
11 x 8 = 88, 22 x 4 = 88, 11 x 16 = 176
4. Making decimals
1.1 x 4 = 4.4, 11 x 0.4 = 4.4.
5. Finding inverses
44 ÷ 4 = 11, 44 ÷ 11 = 4, 176 ÷ 16 = 11
For homework write four closely related
facts to the number sum 13 x 6 = 78 for
each of the 5 headings.
By the end of the lesson children should be
able to:
Use related facts
Halve an even number in the calculation,
find the product, then double it
Answer questions like:
given that 14 x 11 = 154
what is 11 x 14, 154 ÷ 11 or 140 x 11
L.O.1
To be able to count on and back in steps
of equal size
To be able to identify related number
facts and calculate differences
We are going to count from 0 in steps of 7
using a pendulum.
We know
56 ÷ 7 = 8
Write down what other multiplication
and division facts we know.
We know that
7 x 8 = 56
8 x 7 = 56
56 ÷ 8 = 7
Let’s count on….
Now let’s count back from 36 in 3’s
If we stop at 0 write down what the next
number will be?
It should be
-3
Q. How far away from
6 is - 12 ?
Copy into your books:
The difference between -12 and 6 is 18.
-12
-6
0
6
We are going to count on and back in 4’s.
As we do we shall stop to generate and
write down facts and identify differences.
L.O.2
To be able to use closely related facts
(partitioning) and factors – when
completing a mental multiplication.
15 x 12
Work with your table to find two methods to
solve this problem.
3 minutes
Q. Can we rewrite 15 x 12 as
(15 x 10) + (15 x 2) ?
Here we have partitioned the 12.
Q. Can we rewrite it in another way?
Loooook…..
15 x 12 = 12 x 15
so we could partition the 15 and write :
12 x 15 = (12 x 10) + (12 x 5)
We can use factors to multiply.
Write in your book the factor pairs for
15 and 12.
15 =
15 =
12 =
12 =
12 =
Q. How can I write the calculation
15 x 12
using the information we had on the
board?
15 x 12 = 1 x 15 x 3 x 4 =
15 x 12 = 1 x 15 x 2 x 6 =
Are there any more ways?
With your table write as many as you
can think of.
Is the answer always the same?
Let’s try again:
35 x 8
Write the factor pairs for 35 and for 8
35 =
35 =
8=
8=
35 x 8 = 5 x 7 x 4 x 2
Q. Can we rearrange the numbers to make the
calculation easier ? How?
35 x 8 =
5 x 2 x 4 x 7 = 10 x 28 = 280
Replacing each number in a multiplication
calculation with its factors can often make a
calculation easier.
14 x 15
Q. How can we write this calculation
using the factors of 14 and 15?
14 X 15
Can be written as:
2x7x3x5
Q. How does this help us carry out the
calculation mentally?
Q. What are the important factors to look for?
Why?
14 x 15
Can be written as
2 x 5 x 3 x 7 = 10 x 21 = 210
Notice…….
we have put the factors 2 and 5 first in our
calculation!
Work with a partner to answer these
multiplications by using factors. Set them out
sensibly.
Tetrahedra: 15 x 16; 15 x 24; 15 x 26; 45 x 6
Spheres: (also) 45 x 12; 45 x 18; 35 x 12
Prisms: (also) 35 x 16; 35 x 18; 35 x 48
10 minutes
25 x 32
Q. How could we work out this calculation using:
a) partitioning and
b) factorising.
Q. Which method do you prefer?
Q. Would you use the same method every time?
Remember:
Partitioning is reliable and works
for any pairs of numbers.
Factorising works best when one
of the numbers is a multiple of 5
By the end of the lesson children
should be able to:
Use factors, for example:
15 x 6
15 x 3 = 45
45 x 2 = 90
15 x 6 = 90
L.O.1
To be able to round numbers, including
decimals taking account of the context
Write answers in your book:
1.
2.
3.
4.
5.
6.
What is £ 3.85 to the nearest pound?
What is 17.22 m. to the nearest metre?
What is 9.499 l. to the nearest litre?
What is 0.38 kg. to the nearest kilogram?
What is 2501 to the nearest thousand?
What is 642.7cm to the nearest metre?
The bill for a meal was £ 81.13 for twelve
people. They agree to share the cost
equally. How much should each one
contribute to the cost?
Q. What calculation should we carry out?
We should do a division sum.
£ 81.13 ÷ 12
=
6.7608333
Q. What does this answer mean?
Q. How much should each person pay?
Each person ought to pay £ 6.76
Q. If each person pays that amount will it
cover the bill?
If each person pays that amount the total
will be £ 6.76 x 12 = £ 81.12.
Oh dear.
They will be 1p. short!
Tragedy!
Q. If they round £ 6.76 up to the nearest
pound how much is the tip?
Do these in your book:
A car has travelled 343 miles. If it travels 9 miles on one
litre of petrol work out how much petrol it has used to the
nearest litre.
This year John’s trawler has caught 589 tonnes of fish.
He has made 23 journeys to sea. What is his average
catch? How many tonnes, to the nearest tonne, could he
expect to get on his next journey?
Sue’s stall at the fair took £219.51. She had to sell 27
jumpers to achieve this. How much was each jumper?
If she had rounded up her price to the next pound how
much extra would she have made?
L.O.2
To be able to use all four operations to
solve simple word problems involving
numbers and quantities.
To be able to explain methods orally and
in writing.
Look at Resource Sheet 3:1
Read the Initial Information and the Onestep questions.
Q. What information will you use to
answer the three one-step questions?
With a partner write the answers to the
one-step questions in your book.
Now look at questions 4,5 and 6.
Q. Can you answer these questions using only
the Initial Information?
Q. Is further information needed?
Q. Where is the information?
Q. How are questions 4,5 and 6 different from
1,2 and 3?
Answer nos. 4,5 and 6 in your book with a
partner.
2.5 kg of potatoes
cost £1.35
3 litres of milk cost
£1.38
1. How much would
5kg of potatoes
cost?
2. How much would 5
litres of milk cost?
Q. Are these one-step or two-step questions?
For question No.1………
As 5 kg is double 2.5kg only ONE calculation is
needed.
5 kg of potatoes cost 2 x £1.35 = £ 2.70
For question No. 2……..
5 is not a multiple of 3. In this case we need to find the
cost of 1 litre, then 5 litres.
needed.
1 litre of milk costs
5 litres of milk cost
TWO calculations are
£ 1.38 ÷ 3 =
x 5 =
Use calculators to find the answers.
2.5 kg of potatoes
cost £1.35
3 litres of milk cost
£1.38
3. How much would
9kg of potatoes
cost?
4. How much would 9
litres of milk cost?
Q. Are these one-step or two-step questions?
For question No.3….…
9 is not a multiple of 5. In this case we need to find the
cost of 0.5kg. of potatoes and multiply by 18.
TWO calculations are needed.
0.5kg of potatoes cost £1.35 ÷ 5 =
9 kg of potatoes costs
x 18 =
For question No. 4…….
As 9 litres is 3 x 3 litres only ONE calculation
is needed.
9 litres of milk cost 3 x £1.38 = £4.14
When numbers are factors we can find an answer by
scaling up OR down using ONE calculation.
When numbers are not factors we scale down then up
using TWO calculations.
You don’t believe it?
LOOOOK
If 10 buns cost 60p. it is easy to find how much 5 buns or
20 buns will cost.
– ONE step problems.
It is harder to find how much 15 buns will cost
– TWO step problem.
2.5 kg of potatoes
cost £1.35
3 litres of milk cost
£1.38
5. How much would 10kg of potatoes and 6 litres
of milk cost altogether ?
Q. Is this a one-step question?
Try it in your books and see.
Question No. 5 is a THREE step question.
10 kg. of potatoes cost 4 x £1.35 =
6 litres of milk cost 2 x £1.38 =
Altogether they cost
+
=
By the end of the lesson children should be
able to:
Solve “story” problems about numbers in
real life;
Explain and record using signs and
symbols how the problem was solved.
L.O.1
To be able to recall multiplication and
division facts and to find remainders after
division
24 ÷ 6 =
Complete the sum in your books.
Write any related multiplication and division facts you know.
26 ÷ 4 =
How do we write the answer to this division?
We know that 24 ÷ 4 = 6 from the previous
calculation facts. This time there are 2
remaining.
We can write:
26 ÷ 4 = 6 R2
We also know that :
26 ÷ 6 = 4 R2
26 = 6 x 4 + 2
26 = 4 x 6 + 2
33 ÷ 5 =
Work in pairs to do this calculation and to
derive the three associated facts and
record these in your book.
You should have:
33 ÷ 5 = 6 R3
33 ÷ 6 = 5 R3
33 = 6 x 5 +3
33 = 5 x 6 +3
Work with a partner to answer these and
find all the associated facts:
1.
24 ÷ 5 =
2.
34 ÷ 7 =
3.
35 ÷ 5 =
L.O.2
To be able to use all four operations to
solve simple problems involving numbers
and quantities.
To be able to explain methods and
reasoning orally and in writing.
Look at Activity Sheet 3.1
Two year 5 children are going to cook a special
birthday meal for their family of 8.
There are three courses. Eight people want soup
and six want the macaroni cheese.
Everyone wants the pudding. Notice how many
people each recipe serves.
The two children need to buy the right amount of
ingredients to make enough food for everyone.
Q. How can we help the children?
You will work in a small group to find the
answers.
You may need to scale some recipes up or
down.
In the space provided on the Activity sheet
record your calculations and answers with the
units of measure.
You may use a calculator but must still record
the calculations.
Q. Did you use a calculator? Did you use it
for any of the soup calculations ?
If you are merely doubling numbers you
should not need a calculator.
We are going to record the answers on
OHT 3.2.
Q. How else could we write 600g of potatoes?
Q. How much flour is needed to cook the meal?
Q. How much butter will be used ?
Q. How much milk will be needed?
Q. If we can buy flour and potatoes in kilogram
packs only how much of each must be
bought? How much will be left over?
Q. Stock cubes come in packs of 10. How many
are needed and how many are left over?
Q. Butter comes in 450g. packs. How many are
needed and how much is wasted?
Q. Eggs come in dozens. How many are left
after the pudding has been made?
A packet of crisps costs 55p.
A bag of 6 oranges costs £1.25
This week you have been calculating with and
without calculators. The first question you should
always ask yourself should be
“Can I do this calculation in
my head?”
I shall ask you some questions. In pairs write
down quickly how you would do the calculation
without a calculator then do it.
A packet of crisps costs 55p.
A bag of 6 oranges costs £1.25
Q. What would 10 packets of crisps cost?
A packet of crisps costs 55p.
A bag of 6 oranges costs £1.25
The answer is £5.50 and can be done mentally.
Q. What would 9 packets of crisps cost?
A packet of crisps costs 55p.
A bag of 6 oranges costs £1.25
As 9 is one less than 10 we subtract 55p from
£5.50 mentally or with some information
recorded to help.
Q. What would 18 packets of crisps cost?
A packet of crisps costs 55p.
A bag of 6 oranges costs £1.25
We can do this in different ways:
Using factors … 18 x 55p = 2 x 9 x 5 x 11
= 2 x 5 x 9 x 11 = …..
Adjusting …
18 x 55p = (20 x 55p) – (2 x 55p)
= …….
or Partitioning …
18 x 55p = (10 x 55p) = (8 x 55p)
= ……
Do this sum using a calculator but you must write down the
calculation as you do it.
A packet of crisps costs 55p.
A bag of 6 oranges costs £1.25
Q. What would 12 oranges cost?
.
A packet of crisps costs 55p.
A bag of 6 oranges costs £1.25
This is a mental calculation ; double £1.25…
Q. What would 15 oranges cost?
.
A packet of crisps costs 55p.
A bag of 6 oranges costs £1.25
15 oranges would cost…..
This is a three-step sum.
We’ll work it out together.
By the end of the lesson children
should be able to:
Solve “story” problems involving
quantities and units of measure,
Use a mental, written or calculator
method to solve problems.