Primary maths help please

[isitwineoclockyet]

My daughter's homework was all about odd & even numbers, & whether adding & subtracting odd & even will give you an odd or an even answer. So for example, odd + odd = even.

All very straight forward, except that some of the sums had decimals in them (31.3 + 42.6, for example)

DD couldn't do those & asked for our help. DH & I both thought the concept of odd & even only applied to whole numbers, except in certain specific cases, which neither of us can remember but which we thought were probably beyond the scope of the average primary maths lesson.

We asked our yr 9 daughter what she thought & she said she also thought odd & even only applied to whole numbers & asked whether they were supposed to round them.

I've just been & asked the school, & their answer is that if it ends in 1, 3, 5, 7 or 9 then it's odd, regardless of how many places beyond a decimal point the last digit is (so 3 is odd, 0.3 is odd, & so is 0.03.

Can anyone with a maths background confirm for me who is right?

(I should say there is some history here, including previous homework which had a 5x3 grid on it, & the statement underneath "In the 16 squares above.....")

Thanks.

I can't send them this thread, because there are other things on here under my username that I wouldn't want them to see. Past experience tells me it's not likely to happen, but I would rather have an open, sensible conversation about why they're teaching kids that 3.2 is even & 3.1 is odd. It's what I was hoping for this morning, but he just grinned stupidly at me & said that at lower levels it's true that only whole numbers are odd or even , but at more advanced levels it's not. Maybe he was hoping to scare me off by making me feel stupid.

I asked her class teacher because he's the one DD asked me to speak to. They are in sets for maths & are not necessarily taught by the class teacher, so I could just confirm with her that there's no one else I could talk to.

You know what though... I have an awful sinking feeling that the teacher I spoke to is the maths coordinator. I went to an open afternoon they had some years ago about maths teaching in the school & what resources they use, which ones children can use at home etc etc. He was chairing it all. Bugger.

May try googling Scholastic maths resources & see if I can find the sheet.

GoAndDoSomeWork (great name by the way!) when I asked him this morning, he was absolutely clear that decimals can be odd or even. I will see if I can find the sheet though - might give me an idea what Scholastic intended teachers to do with it!

He's definitely wrong about the odd even thing

But maybe thepoint of the sheet was what you referred to in the bginning part of your post ie seeing the patterns that happen when you add numbers that END in an odd or even number, regardless of decimal place.

Obviously 3.1 add 4.1 makes 7.2 which is still an odd number. BUT the .1 + .1 ends up being a .2 IYSWIM

and a .3 + .5 would give you .8
but a .3 + .4 would give you .7

I can see the value in exploring (for example) what happens when you take away 0.3 from 4.5 or, for that matter, 300 from 4500, and showing that the principles you've learned about adding and subtracting odd and even numbers can be useful when you are looking at other place values. But that doesn't actually make 0.3 an "odd number" any more than it makes 300 an odd number. Or any more than dressing in yellow makes me a banana.

Ask him at what level odd and even aren't integers. I'm really interested to know, as I'm certain that at degree level it is. Will send it to my friend who is a maths lecturer if you like....

I've been through various possibilities in my head about why the sheet was designed how it was, & what the kids were supposed to be taking from it, but I'm still properly confused.

If all they were meant to do was notice that odd + odd = even, then there are enough whole numbers (possibly an infinite number of them...???) that they could have used as examples.

If they were meant to work out that 3.5 wasn't a whole number, therefore couldn't be odd or even, then the sheet (and the teacher) should have said that.

The teacher definitely thought the point was to teach them that anything ending in an odd number was an odd number, even if it was after a decimal point!

DeWe the teacher was implying that by year 5 you are advanced enough to know that even and odd does not only apply to whole numbers. (though I have a DD in year 9 who certainly thinks it does!). If you think your friend could shed some light on it that would be great.

Thanks again for everyone's input.

If the point of this maths sheet was not clearly understood/explained by this teacher, how can your poor DD ever trust any of the maths lessons she will receive from this teacher.
She will never really be 100% certain that he is teaching them correctly will she? I think you should complain.

So, according to him, what happens with 42.6 + 3 = 45.6?

Presumably either

(a) 3 is an odd number, 42.6 is an "even number" but 45.6 is also an "even number" so you've added an odd number to an even number and got another even number and the world is probably about to end

or

(b) 3 is an odd number, but 3.0 is mysteriously an even number. So adding an "even number" to an "even number" produces another "even number" and the world is probably safe, but on the other hand he can't say whether the number three is odd or even, which is an interesting point of view.

Herd, you are absolutely right. In the teacher's world;

42.6 is even
3 is odd

45.6 is even, therefore you have indeed added an odd number and an even number together and got an even number.

This is the example I need to take in & ask him to explain isn't it?

If 3 is actually 3.0, then the whole concept of odd and even is redundant, because any number at all could have an extra decimal place after it, with a zero in it, meaning every single number is even.

QED

That is a very strange explanation and I have never heard ot if...if it is on a worksheet it is even more worrying!
I guess you will have to deal with this teacher for the remainder of the year....mistakes do happen but if he really believes he is right I think you should be keeping a close eye on your child's Maths!
I have seen a few errors on my own Dd's Maths sheets but they have never been that serious....more in the line of information missing to complete questions e.t.c.

A quick update.....

The teacher has gone through the homework & said that, for example, 35.1 is an odd number, 42.6 is even etc etc. He's going to explain it again tomorrow for the benefit of those who were "confused" by it.

My DD, who was convinced this morning that only whole numbers can be odd or even has just confidently told me that 37.8 is an even number.

I asked a couple of yr 6s while I was there (children I know well - I didn't just randomly assault some!). One (top maths set) said he didn't know whether something ending in .6 would be odd or even, & another (middle set) said she thought it only applied to whole numbers.

How can it be this hard to teach primary aged children something so simple?

I've just googled and found this www.factmonster.com/ipka/A0876700.html right at the bottom it states that fractions cannot be odd or even as they are not whole numbers.

Sheesh, how hard can it be, really! BUT, if its a scholastic worksheet then they need pulled up PDQ.

Your poor dd must be very confused.

Thanks heymammy. I've just shown DD that, as well as showing her some of the other messages, where I thought she could understand them & they wouldn't confuse her more.

"A number (i.e., integer) expressed in the decimal numeral system is even or odd according to whether its last digit is even or odd. That is, if the last digit is 1, 3, 5, 7, or 9, then it's odd; otherwise it's even. The same idea will work using any even base. In particular, a number expressed in the binary numeral system is odd if its last digit is 1 and even if its last digit is 0. In an odd base, the number is even according to the sum of its digits ? it is even if and only if the sum of its digits is even."

Perhaps he got it from wiki?

I think a decimal number system is one that is based on the number 10, so each digit represents a number of tens (e.g. 534 is 5 hundreds, 3 tens & 4 units). So I think a number in a decimal number system can still be a whole number & doesn't necessarily have to have a decimal point somewhere in the middle of it. Can someone reassure me that I am right with that?

I vaguely remember learning about binary systems, but don't recall understanding them too well!

I think that explanation (it's odd or even if its last number is odd or even) is pretty much exactly the teacher's explanation though.

My word ! He's just wrong! I have a masters in Maths, it makes me shudder! Integers, people, integers!

Only integers are even or odd.

This is absolutely shocking. I only have an AS in Maths but it doesn't take a genius to know that even number do not include any old number with a decimal after it.
So 5.5 is odd but 5.50 is even despite these being EXACTLY the same number?

Now we all learnt that an odd number plus an odd number will add up to an even number, correct? 3+5=8 11+5=16 and so on.

lets try 3.5 (supposedly odd in this strange new system) +3.5
We have a total of 7. An odd number if ever there was one.

We all know that an even number and an odd number will make an odd number. 10+3=13 7+4=11 etc.

So we try 11.2 (now an even number) and 5 (an odd number) and we get 16.2, which ought to be even in this system.

It goes against all the rules and against common sense.
5 is odd but 5.0 is even?

Perhaps the teacher could point out to you where this "topic" features in the national curriculum for maths?

I have a first class degree from Oxford in maths. I also have a masters from Cambridge, with distinction, in maths.

odd and even applies only to whole numbers. The teacher is talking nonsense.

I think the teacher misunderstands the definition but is trying to get the point across to the children that odd+odd=even. But the teacher is utterly, utterly misguided using decimals to do this, because 1.09 + 1.7 = 2.79

So if the "rule" cannot apply to decimals unless you pad them with leading zeros which is a pointless exercise.

If my children were being taught this nonsense I would complain, in writing to the head, using an example similar to the above to prove the misunderstanding in the teachers' logic. I would then take my children's mathematical education into my own hands for the rest of the school year.

Katandkit - when the teacher goes over it again tomorrow for the "confused" children, I will suggest my DD asks him to run through 3.5 + 3.5 for her.

Am considering a letter to the governors, though I don't have much faith it will achieve anything. If the teacher had given any indication he was prepared to discuss it with me (& ideally change his mind, obviously!) then I'd have been happy to leave it at that, but he was really dismissive of what I was saying.

He basically said I had obviously never come across sophisticated enough maths to know that a non-whole number could be odd or even. (I have BA and MSc in subjects with lots of maths.....)

He probably doesn't have anything more than a gcse in Maths if this is his understanding.
I reckon he sees adding a load of decimals as "extending" the topic of odd and even numbers for more able learners. It seems to be a general rule that if you want to make a topic more challenging, whack some decimals in it.

I am a secondary maths teacher.
Teachers like this make my life hell.

He is wronger than a wrong thing dipped in wrong juice and covered in sprinkles of wrongness.

Vincentvangogh - I have considered taking the whole of my children's education into my own hands, many times!

Bob - you made me smile!

Also odd plus odd makes even, as we know.

2.25+2.25=4.5 (which would be odd)

even plus even makes even

2.250+2.250 = 4.5 (the zero is meaningless) which is "odd".