If your a parent of a primary school age child then the chances are that you are involved in assisting them with their homework. Maths homework, in particular, can be a real struggle for some parents. I have to admit that there have been occasions when I’ve seen what they have to do and not had a clue. Yes, a grown man not knowing how to do primary school maths. But, the real problem can often be that the way we (the parents) were taught mathematical methods differs from modern approaches. We may not like it, but we have to accept it and try and adapt our approach. This post addresses some differences between how I would do some maths functions and how our daughters’ primary school advises they are done.
Most schools have a website nowadays and quite often this is an underutilised resource for parents. Many schools put up advice on how subjects are taught and how parents can help with this learning. Our daughters’ school does this and their maths calculations booklet is what I’ve based this post on; taking their approach and comparing how I would do it.
In the first of a two-part series, we’ll be looking at addition and subtraction. Check back next Monday for part 2.
Adding numbers together – the bread and butter of mathematics. For me, column addition is a tried and tested method that just works. But, as I alluded to in my post about maths homework some children get some methods whereas as other just don’t sink in. So let’s look at an example and work it through with my column addition and how the school teaches it:
49 + 31 + 25 =
Using column addition this is how you would approach this:
First, you add the units column together and put the results underneath, if the number is greater than 9 then put the units figure from the answer and carry the 1 (tens) to the next column. Then add the tens column including any number you carried over. Again, if the tens add up to more than a single digit number, put the unit value in the tens column of the answer and carry the tens digit to the hundreds column. Then add up your hundreds column including any value you carried over to that column.
This method has always seemed to logical to me and works for any size of number. But, it appears teaching has moved on and number sentences (as in the sum all on one line) is in fashion. So here’s how our primary school teaches it:
You start by breaking each of the numbers to be added into two number sentences, one for the tens and one for the units. The principle being that this simplifies the sums the kids have to do. You then take the result of adding the tens and add that to the result of adding the units and you have your answer.
But wait, because you can also record it like this too:
Interestingly, this is remarkably similar to column addition – wouldn’t you agree?
So now we’ve tackled addition, let’s move on to it’s opposite – subtraction.
Once again, when it comes to subtraction my approach is to use column subtraction. For me, it’s a tried and test method that I find works and I have to say, Delilah, currently in year 5, also knows this method too. Let’s look at an example:
73 – 26 =
With column subtraction I would do this:
Column subtraction can be tricky to understand, so let me explain. With column subtraction you take the number below from the number above in each column. In this example you can’t take 6 away from 3 – so what do you do? Well, you borrow 10 from the tens column and add that to the 3 – making 13. Now you can take 7 from 13 and the answer is 7. Obviously, now you borrowed 10 from the 70 in the tens column you are left with 60, so 6 take away 2 is 4 – and you have your answer – 47.
I have found that this method of borrowing numbers from the column to the left is where kids fall down with column subtraction. So I can understand why this alternative is taught too:
This alternative method is one I like because it pretty much how I would do subtraction in my head. Children are taught to understand that subtraction is finding the difference between the smallest and largest number. Simply, you find the difference between your lower number up to the next 10 (40) and note it down. Then, find the difference between the highest number and the nearest multiple of ten below (70) and note it down. Now, find the difference between the two multiple of ten you rounded to and note that. Finally, add all numbers you noted together.
A similar method with a number line is to jump to the next multiple of ten like this:
So there you have it, a comparison between how I was taught addition and subtraction compared with how my children are taught it today.
Check back next Monday for part 2 of this mini-series where I will be covering multiplication and division.