June, 2009 | Maths Blog

Using a calculator: Take 1

Most children have access to a calculator, and there are very good reasons why their use should be encouraged. However, there is still a great deal of opposition to them. I certainly would not advocate their use to solve simple sums which can be done mentally or on paper, but they are great for investigations and improving attitudes to maths.

This first calculator page uses the calculator as a quick check for mental arithmetic. Taking one from a number might appear very easy, but with large numbers such as 20200 it requires a good knowledge of place value.

This page also introduces the idea of the calculator as a function machine, in this case a ‘take 1’ machine. With many calculators by keying in the minus sign (-) followed by 1 then the equals sign the answer -1 is shown. Ignore this, don’t clear the answer, and type in another number eg 450 and press the equals sign and the answer will come up (449). Continuing in this way saves time as it more than halves the number of entries to type in. It can, of course be applied to any subtraction which has to be done on numerous occasions.

Using a calculator: Take 1

Coming Soon: Bodmas, Decimal Fractions and Using a Calculator

Coming up this week is our second page on Bodmas for year 6 children plus rules of divisibility for multiples of 3 and 6. We also have some decimal fractions on tenths, suitable for Year 4 as well as a page on Using a Calculator efficiently. Most children have access to a calculator, and there are very good reasons why their use should be encouraged. However, there is still a great deal of opposition to them. I certainly would not advocate their use to solve simple sums which can be done mentally or on paper, but they are great for investigations and improving attitudes to maths and I will be publishing some more on Calculators in the near future.

Maths worksheet: Order of Calculating (Bodmas) 1

2 + 4 x 3 =
The acronym BODMAS probably conjures up memories of school maths for many people and it is still as important today. It stands for:

Brackets
Of
Division
Multiplication
Addition
Subtraction.

It is a convention to ensure everyone carries out a question such as that above in the same order. Numbers in brackets are worked out first, followed by multiplication and division with addition and subtraction last.
One way to do the question is: 2 + 4 = 6. 6 x 3 = 18.
It can also be done like this: 4 x 3 = 12. 12 + 2 = 14.

If you use a calculator and key in 2 + 4 x 3 you might get 18 or 14, it depends on the type of calculator you use (simple of scientific). So which is ‘correct’?
Answer: 14
So with 2 + 4 x 3, the first thing to do is 4 x 3, then add the 2.
To make this easier we often put brackets round parts of the question, to make it clearer, like this:
2 + ( 4 x 3 )
Primary children might not be introduced to the term BODMAS but they should be working in the correct order.

Order of calculating (pg 1)

News: Home Education Review

A review of home education in England will be recommending that there should be a national registration scheme for home educators, forcing parents to register with their local authority.
The government set up a review to find out how effective local authorities are in monitoring home educated children and whether home education was being used to hide, “child abuse such as neglect, forced marriage, sexual exploitation or domestic servitude”.
At the moment local authorities must ensure that all children are getting a suitable education, either in or out of school, but they have no statutory duty to monitor children who are taught at home.
Ann Newstead, for home education group Education Otherwise, said: “If one thing could come out of this review which would mean it was not a complete waste of public money, it would be that the decision to home educate is treated with respect and as a positive choice.”
Surprisingly no-one seems to know how many children are being educated at home; figures vary from 20 000 to 80 000.

Year 1 maths worksheet: Money problems (1)

Money is a great way to encourage children with their addition and subtraction and of course, it is the spending of it when we most use our mental arithmetic skills!

This worksheet is for Year 1 children who are confident with counting and adding small numbers. It uses three coins, the 1p, 5p and 10p. Encourage trying to add in order of size, starting with the largest coin and, if necessary, counting on from that.

Money problems (p1)

Year 3 Maths Investigation: Across and Down

Investigations are a great way to develop logical thinking and improve systematic lines of enquiry.
This is a fun investigation for children from Year 3 upwards (7+ yrs). The task is:
Put in the numbers 0, 1, 2, 3 and 4 in the squares on the grid so that the total across is the same as the total going down.
Children will probably start this mini investigation with a lot of ‘trial and improvement’ and then come up with some correct solutions.
There are several key aspects to the logical thinking behind this, including:
1. Add up the total of 0, 1, 2, 3 and 4. It comes to 10.
2. This means that if the total across and the total down are equal and the corner number is zero, they must both add up to 5.
3. By working methodically with zero in the corner 8 arrangements can be found.

There is also a print-out of large numbers which can be cut out to help children move the numbers about without having to write down everything they do.

Investigation: across and down

Maths Worksheet: Subtract a Single Digit (year 2)

Once children are confident with subtracting single digits from single digits they can move on to subtracting from 2-digit numbers. This maths worksheet has a number line to help. Children can either start with the larger number and count back, or start with the smaller number and count on.

The next stage would be to start with the smaller number and know how many it takes to reach ten and then add on from there. E.g. 13 – 8. Start at 8 and know that add 2 will make ten. Continue from ten and add on the unit digit, in this case 3, to make 2 + 3 = 5. 13 – 8 = 5. A combination of knowing and counting on may well take place: many adults use this technique.

Subtract a single digit from a teen (pg1)

Coming Soon: Maths Worksheets on Money, Decimals and Bodmas

Next week we have a wide range of topics for our maths worksheets. There will be a neat page on counting money for year 1 children and a subtraction page for year 2.

There is also a great mini-investigation using small numbers which is ideal for year 3 children; this also has some ideas to follow, suggested methods of working and numbers to print out to help.

For older children we dip our toes into the wonderful world of BODMAS and the order in which calculations should be completed – excellent for those year 6 children who have finished their SATs.

Also coming soon is a tricky page of adding decimals mentally, a good test of knowledge of place value as well as knowledge of number bonds.

Year 3 maths worksheet: Multiplying by 10

We’re back on to the idea of multiplying a whole number by ten, probably one of the most important concepts in primary maths. Of course, by now we all know that each digit moves one place to the left and a zero is placed in the units, acting as a place holder for the other digits. It is easy to say ‘add a nought’ but this just doesn’t work later when decimals are multiplied by 10 and it doesn’t help to explain dividing by ten, when each digit moves one place to the right. Children can do simple multiplication by ten quickly, but they do need to understand what is happening.

Multiply by ten (p1)

Year 1 maths worksheet: Longer and shorter

This page adds to our selection of measurement worksheets for year 1. It looks at two terms, longer and shorter, and should be used in conjunction with plenty of discussion in the home. Ask questions such as ‘Which is the taller candle?’ and make requests, eg ‘Pass me the shorter pencil, please’ during the everyday activities you do with your children.

Longer and shorter