Using a calculator - Bridlewood Primary School

Using a calculator - Bridlewood Primary School
The National Strategies | Primary
Helping children with mathematics: Year 5 to Year 6
1
Using a calculator
Key learning
Use a calculator to solve problems, including those involving decimals;
interpret the display correctly in the context of money and measurement.
Check that your child can:
●●
use a calculator to add, subtract, multiply and divide numbers,
including decimal numbers;
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read and explain the numbers on the display in the context of money
or measures (for example, explain 5.5 as £5.50 or 5 metres and 50
centimetres).
Reading the display
Enter on a calculator a number with one
or two decimal places.
Pass it to your child and ask them to suggest
what the number could represent as
money or measures. For example:
54.04 could be £54 and 4p, or 54
metres and 4 centimetres.
Swap roles and try different numbers.
Try numbers with more than two
decimal places.
© Crown copyright 2008
00132-2008FLY-EN
2
The National Strategies | Primary
Helping children with mathematics: Year 5 to Year 6
Notes for parents/carers
Using calculators helps children to learn more about how numbers work
as well as performing calculations during problem-solving.
Estimating the answer first helps you to know if the calculator answer is
likely to be right. Encourage your child to estimate roughly what size
answer they expect, before using their calculator.
Let’s estimate and check…
Save some supermarket till receipts and fold them to hide the totals. Then
both of you work out the approximate total cost. Work separately, jotting
down the rough amounts you are adding up and the total. (For example,
you might assume £3.61 is roughly £4.00 and £0.48 is about 50p.)
Compare your answers and how you worked them out. Check with the
calculator. How far were you out? Who was closer? Would it help to do this
in the shop?
For practice in using the calculator, ask your child to start with the total
and work through the receipt, subtracting each price in turn. Do they get
back to zero?
Let’s divide…
●●
If eggs cost £1.85 per half-dozen, how much does each egg cost?
●●
The calculator shows 0.308 333. What does that mean?
A calculator game
To play you need basic calculators (remember that many mobile phones
have calculators) and some sticky notes.
Write the digits 2, 3, 4, 5, 6 and a multiplication sign (×) on the sticky notes
and arrange them to make a multiplication calculation such as:
00132-2008FLY-EN
© Crown copyright 2008
The National Strategies | Primary
Helping children with mathematics: Year 5 to Year 6
3
Use your calculators to work out the answer to this calculation.
By rearranging the numbers and deciding where to put the × sign, see if
you can produce a calculation with a bigger answer.
The object of the game is to see who can find the biggest possible
answer, each time using the same five digits (in any order) and ×.
Try the same game with a different set of digits, or use the same set of
digits with division to find who can get the smallest answer.
‘Let’s talk about maths’
Take every opportunity to use calculators in
the home, to solve practical problems in
everyday life, working out:
●●
and checking household bills;
●●
how many miles your car runs on a
litre of fuel;
●●
how much it would cost to take the
family to the cinema.
© Crown copyright 2008
00132-2008FLY-EN
4
The National Strategies | Primary
Helping children with mathematics: Year 5 to Year 6
Who can get closest?
Ask your child to key the number 6.8 into a calculator.
Write down another number to multiply the first number by (e.g. 8.4).
Before doing the multiplication on the calculator, both of you should
predict the whole number that the answer will be closest to.
Compare your predictions with the answer. Whoever is the closer scores a
point. Have ten goes, using different numbers, each with one decimal
place. Who wins? Talk about your strategies.
Ask your child to key the number 74.8 into the calculator.
Write down a number between one and ten with one decimal place (e.g. 5.3).
Each of you chooses a number to divide 74.8 by to get an answer close to
that second number. Use the calculator to check. Who is closer? They
score a point. Have ten goes. Discuss your strategies.
Make up your own rules.
Repeating rules – what happens?
Enter any number into the calculator.
Add one and divide by five.
Using the answer displayed, repeat the rule: add one and divide by five.
With each answer, keep repeating this rule. What happens?
Now use the same rule with a new start number. What happens?
Use the rule: add one and divide by six. What happens this time?
Make up your own rules and see if you can find a pattern each time.
00132-2008FLY-EN
© Crown copyright 2008
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