# Mumsnet Talk

## when the teacher is wrong, and a bit arrogant...

(35 Posts)
withgreatpower Wed 09-Jan-13 21:49:58

Today my DD's teacher (Year 6) lost her patience with DD.

The pupils were given a question like: "Work out 2+3x5 ". The teacher said that you have to put brackets like this: " 2+(3x5) " otherwise the question doesn't make sense. My DD said (correctly!!) that you don't need brackets, as you have to do multiplication before addition anyway. The teacher insisted, DD insisted, teacher snapped and said something like "I did A level Maths, so I know what I'm talking about".

DD stopped trying to explain...

DD was a bit sad at this (she very rarely/never gets teachers cross). We (DD and I) talked about this, and I used it as a lesson to learn:

1) just because somebody is a teacher, doesn't mean they don't make mistakes

2) it's just a mistake, everybody makes mistakes

3) when you don't think something is right, go check in other ways, don't just trust one source of information

I also added that maybe the teacher was tired, and was having a bad day, so she lost her patience. DD asked "So this teacher is always tired?" (teacher doesn't have much patience in general).

I just wanted to share this story - I'm not too bothered by the mistake, but I keep telling my children that, if something the teacher says doesn't seem right, they should double check by asking other teachers or by looking in Maths books etc (I'm talking about myths like you cannot do "4 minus 6" -- of course you can! you get a negative number, but you can do it!; or that the answer to 6 divided by zero is zero -- AAAAAAAAHHH No it's not zero, it's infinity)

Sorry, not a very interesting post, but I just wanted to share ...

learnandsay Wed 09-Jan-13 21:55:50

It's a brilliant lesson in life. I can't remember the film but there was a line in one which went "being always right isn't a bullet proof vest."

Authority trumps technique and knowledge until the wheels fall off the wagon, at which point it all becomes fair game.

Wed 09-Jan-13 22:06:19

My DS rates his teachers on how they react to being questions that they don't know the answers to. That would drive him nuts, though. It is, as you say, a good life lesson, but the teacher could earn a shed load of respect if she came back and admitted she was wrong....

Wed 09-Jan-13 22:07:17

Or indeed he. Just realised that you didn't specify gender of teacher.

Wed 09-Jan-13 22:17:57

We had a few times that dd1 corrected her teacher about Maths, starting in Recpetion with 'my mummy teaches Maths and she says ....'

I talked quite a lot to dd1 about making sure that she is incredibly polite to teachers when she is trying to explain to them about a mistake they may have made. She also learnt to check with someone else as she knew that her teacher only had GCSE Maths and by year 6 I'm convinced dd1 understood the Maths better than the teacher.

It is rather bad that any teacher in year 6 doesn't know the rules of BIDMAS, and I hope this teacher will come back with an apology for getting it wrong. It's things like this that annoy the next teacher those children will have as they will all say "Miss x said we had to do this...." and I have to try and find a diplomatic way of saying "well Miss X was wrong, that's not the rule at all".

learnandsay Wed 09-Jan-13 22:28:36

I don't think that being in authority and admitting that one is ignorant or incorrect are all that compatible. I'm not sure why that is the case. I suspect it's because what one subordinates might take for reasonableness another might take for weakness and in advance the authoritarian has no idea who will perceive what. So, in preparation, he or she simply deems all statements not made by the teacher to be incorrect.

Wed 09-Jan-13 22:29:05

I had to do that with DS at one stage - "Mrs X taught us this way, which makes sense, but Mr A said to do it a different way..."

"Well, DS, given that Mrs X is the head of maths, and Mr A is an arse English specialist, which one do you think we should choose to ignore? "

Wed 09-Jan-13 22:30:48

learnandsay I don't agree. "I don't know, but let's find out together" is a valid answer and one which generates respect, IMO/E

HolofernesesHead Wed 09-Jan-13 22:31:12

I tell my dcs when their teachers' grammar is wrong.

Maria33 Wed 09-Jan-13 22:37:06

Learnandsay. I am a teacher and I sometime make mistakes cos I'm a human being and there is a limit to my god-like omniscience . When I get things wrong, I correct myself and move on. My primary job is to educate, not to wield authority. The kids still seem to respect me but more importantly, they learn the right thing

Maria33 Wed 09-Jan-13 22:37:48

See - I made one there...

learnandsay Wed 09-Jan-13 22:38:23

I think we're also talking about a situation where the teacher actually thought that she was right. It can be very difficult to persuade anyone that their cherished view is in fact wrong. And I'm guessing that it's even more difficult if the critic is eight years old. Why do we always have adult experts on news channels rather than clever nine year olds?

Maria33 Wed 09-Jan-13 22:42:08

enjoying the idea of a clever nine year old on the news. But teachers are used to exposing themselves to ridicule and challenges from kids. It's par for the course and sometimes clever kids are right. Damn those clever kids

Amerryscot Wed 09-Jan-13 22:45:57

2+3x5 does really need brackets.

You can't just look at the expression and decide that the multiplication needs to be done first. The BIDMAS rule doesn't really apply in this situation.

I would have to say that in this example of pupil tattle tailing is that parents shouldn't believe everything that happens in school, and therefore teachers wouldn't believe everything that happens at home.

Wed 09-Jan-13 22:52:44

See I thought 2+3x5 was 25 whereas 2+(3x5) was 17.

Clearly not as good at maths as I thought.

And no, I'm not the teacher...

withgreatpower Wed 09-Jan-13 22:53:44

learnandsay, I see your point. The teacher needs to have authority to be in charge.

However, and maybe it's not totally related, I remember reading that the majority of plane crashes happen when the more experienced, senior pilot is flying the plane, because the younger pilot (who might have understood there is a problem, and wants to tell the pilot how to avoid crashing) doesn't trust his knowledge enough to question the pilot's decisions. The authority of the senior pilot is actually dangerous in this case, as the younger pilot can't conceive that he himself is right, and not the experienced pilot. That's why I think this was a good lesson for my DD to learn, not so much for the teacher.

withgreatpower Wed 09-Jan-13 23:00:43

Amerryscot, I might be wrong... but I think my DD was right. Have a look at www.bbc.co.uk/bitesize/ks3/maths/number/order_operation/revision/2/.
However, I am ready to listen to your explanation.

Wed 09-Jan-13 23:05:28

Teachers are often wrong - they are human beings. We live in a culture which accepts human error and encourages polite, constructive correction.

Someone I know teaches maths in a British boarding school that has a lot of Malay/Chinese pupils. They never correct teachers. They will copy down 2+3=62 without a murmur. We wouldn't want our children to be that accepting of a teacher's authority.

On the other hand, some children challenge obnoxiously. I did this to our utterly shit A-Level German teacher, who was eventually so exasperated she sentenced me to teach the next lesson, on the subjunctive. It backfired on her though, as I did it, and taught her things she didn't know...

Wed 09-Jan-13 23:06:18

BIDMAS means you are never in doubt. You only have to use brackets where the normal rules don't apply.

Wed 09-Jan-13 23:41:59

Amerryscot I have to say that it really does NOT need brackets at all. BIDMAS applies in every calculation you ever see, so multiplication ALWAYS needs to be done before any addition or subtraction.

Wed 09-Jan-13 23:43:05

Out of interest, why would you think the BIDMAS rule wouldn't apply in this case?

Clary Wed 09-Jan-13 23:52:55

Of course BIDMAS applies! If you want 25, that's when you need the brackets

See this is when I am glad I teach secondary - if you teach yr 6 the chances are that the brightest pupils will exceed your knowledge in some area (for me it would probably be science or maybe ICT!) and yet you still have to teach them!

This is not a problem in secondary thank goodness

OP I agree, your DD needs to learn that teachers are not always right (I sometimes can't answer a question but try to be honest) and also how to deal with that situation.

StarsAboveYou Wed 09-Jan-13 23:54:04

It doesnt need brackets. BIDMAS means you work through each in order if they are present. So if there is only addition and multiplication then you just need to remember to multiply first then add and not simply complete the sum as it is written.

boxoftricks Wed 09-Jan-13 23:59:28

Isn't the teacher just putting brackets in as a reminder that you do the multiplication first? To break the sum down?

Thu 10-Jan-13 08:16:17

I teach teenagers and I am not afraid to say, 'I don't know' or ,'are you sure? Let's check that'.

All teachers should IMHO.

<not very useful>

realcoalfire Thu 10-Jan-13 10:03:01

You don't need brackets obviously, but perhaps the teacher was just telling them to put brackets in as a technique, to make it look clearer and less likely they will make a mistake

realcoalfire Thu 10-Jan-13 10:17:03

OP wrote the answer to 6 divided by zero is zero -- AAAAAAAAHHH No it's not zero, it's infinity)

That is wrong .6/0 is undefined not infinity.
Undefined means that it is not possible (unsolvable), while infinity just means without end or 'unboundedness'

changejustforyou Thu 10-Jan-13 10:26:26

ha realcoalfile, was just thinking about that "infinity" stuff. That's what I used to think. Whilst revising with dd for her entrance exam I read about it in wikipedia. I didn't really understand it, but realised that I was wrong in saying infinity....

drjohnsonscat Thu 10-Jan-13 10:33:22

I don't know what bidmas means but surely whether you do the multiplication first depends upon what the sentence is supposed to mean.

If you mean that three children had five sweets each and then their mother gave them another two then you do the multiplication first.

If you mean that one girl had two cakes and one girl had three cakes and they decided to pool their cakes and then cut each cake into five to share it among the class so how many slices do you end up with then you can do the adding first.

mummytime Thu 10-Jan-13 10:38:43

drjohnsonscat you have translated it into a number sentence, however as written the rule is Brackets Indices Division Multiplication Addition Subtraction, if you want to do the addition first you do need brackets. It is often a good idea to make sure you use brackets to make sure there are no mistakes.

6 divided by 0 can be anything between 0 and + or - infinity; or so I was told at A'lvevel.

Houseworkprocrastinator Thu 10-Jan-13 10:43:54

BIDMAS? what happened to BODMAS?

Think i might be so out of date with math. Is it possible the teacher was explaining what goes first and was asking the class to put the brackets in to make sense of it?

Teachers are only human though and do make mistakes. my daughter was told in school that a word she said was not a real word. We looked it up together... it is in the oxford dictionary and originates from the 17th century. I did tell her people make mistakes and not to go in the next day and tell her she was wrong.

withgreatpower Thu 10-Jan-13 13:13:32

realcoalfire, thanks for that! You are right! It's not correct to say that 6/0 is infinity. Division is not defined if the number you are dividing by is zero.

It's true that 1/x (or 6/x) approaches infinity as x decreases to near zero, but if x ever exactly gets to equal zero, the answer becomes undefined.
(I looked it up here, by the way www.newton.dep.anl.gov/askasci/math99/math99259.htm (post by Bob Avakian ).

Well, it's good to learn something!

trinity0097 Thu 10-Jan-13 20:53:38

The I in BIDMAS stands for indices, however the O in BODMAS was never clear as to what it stood for (e.g. Over, of are just two examples I heard as a child)

tinytalker Thu 10-Jan-13 21:36:15

Thank God I teach pre-prep is all I can say

cory Thu 10-Jan-13 22:12:27

When I was a child I always thought it was the teachers who couldn't admit they were wrong who came across as really insecure and lacking in authority. When a teacher was relaxed enough to occasionally admit limits to his knowledge, I tended to assume that he probably knew rather a lot... A lifetime in education has confirmed this hunch.

It's like children don't necessarily trust the authority of the teachers (or parents) who shout and rant and dish out punishments all the time: even very young children are savvy enough to suspect that is a sign of weakness.

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