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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

Original poster

to point out to the teacher that a square is a rectangle?

216 replies

GooseyLoosey · 09/05/2011 15:11

Part of ds's homework was to draw on a grid 2 rectangles with a perimetre of 8cm. He drew a 3x1 oblong and a 2x2 square.

Aside from the fact these were the only possible shapes without using 1/2 squares, the teacher marked his homework as incorrect as a square was not a rectangle.

Ds (who is a perfectionist) read this and was not at all happy. He shouted "it is, I know it is, it is. Mummy, I'm right".

Would I be unreasonable to tell ds to ask the teacher why a square is not a rectangle? Or are we completely wrong and squares and rectangles are mutually exclusive?

(PS - I really don't expect teachers to always be right - God knows I am not but this teacher is the school's maths co-ordinator).

OP posts:
senua · 09/05/2011 16:02

"Tell your son yes, he's quite right, but language is slippery sometimes and generally when people refer to rectangles they do mean two sides longer than the other two."

NO!Shock Mathematical language is very precise and unambiguous.

JoanofArgos · 09/05/2011 16:03

Which would be awful, because if someone said to them as an adult 'I need a rectangle fetching, please', they might not know that they could have fetched a square!

juuule · 09/05/2011 16:04

I agree with Senua. Also there might be other children in your ds class who also drew a square but had it marked wrong, too.

Donki · 09/05/2011 16:04

Oh heavens - but if you are of a scientific/maths bent, there may be worse to come....

(Physics pedant who had been annoyed in the past by biology colleagues getting electricity horribly wrong)

JoanofArgos · 09/05/2011 16:06

Not the mathematical language in itself senua, but commands and instructions and terminology.

Anice · 09/05/2011 16:06

wait until you get to rounding...!

Donki · 09/05/2011 16:06

And every day language is frequently at odds with the precise scientific usage. I give you:

weight and mass as an example!

And a retort is not a snotty reply in chemistry.

Goblinchild · 09/05/2011 16:07

Tell the teacher. Education is a right for all, and a life-long experience.Smile
It is a bit of a litmus test, a good teacher doesn't mind being corrected if it's done politely.

JoanofArgos · 09/05/2011 16:11

Well, go in and tell her off if you want, don't expect her to like you or the kid any better for it! My daughter still remembers the child in year 5 who interrupted the teacher who was explaining the three states of matter to shout 'there are four! there's plasma!' - at which the teacher broke off to say yes, fair point, there is plasma, but there won't be any plasma in the experiment we're doing in the classroom, so we need to focus on these three.....

What's achieved? Kids all think the other kid is a bit of a prick and show-off, kid knows about plasma, other kids will learn about plasma later when it is relevant, teacher is probably justifiably irritated!

marcopront · 09/05/2011 16:16

Insomnia11

Yes you can do a venn diagram. Within the set of rectangles you have the set of rectangles and it's compliment which is oblongs.

A rhombus is a special parallelogram where all sides are equal and a rectangle is a special parallelogram where all angles are equal. So a square is the intersection of rhombuses and rectangles.

I'll try and find a diagram.

Want2bSupermum · 09/05/2011 16:21

A rectangle is a quadrangle with four 90 degree angles. A square is a type of rectangle that has four equal sides.

I could go into more detail but I don't want to bore everyone with my knowledge of quadrangles. I wouldn't have your son correct the teacher but I think you as a parent should have a quiet word.

marcopront · 09/05/2011 16:23

Try this

hotmath.com/hotmath_help/topics/quadrilaterals.html

worldgonecrazy · 09/05/2011 16:25

Of course, from another point of view, DS has learned a very important lesson: a person in authority is not always correct and should be questioned if you believe them to be wrong. He is also learning the lesson that even when he is right about something, people in authority can still be tossers.

(And also what fab parents he has to support him in this.)

juuule · 09/05/2011 16:26

I would hope there are more
"a good teacher doesn't mind being corrected if it's done politely." type of teachers around.

joanofargos I don't think that the op is hoping the teacher will like her and her ds any more or less for mentioning the error. And you say "other kids will learn about plasma later when it is relevant," surely its relevant now to the child who already knows about it. You need to be able to trust what a teacher is telling you otherwise you might not bother to remember it (might not be true). The only way to do this is to get the info the teacher is giving you to fit with the info you know.
Maybe the child in your dds class has been the reason your dd remembers about plasma. And not all the other kids in the class would have seen it as showing off and I think that teacher handled the situation well.

RitaMorgan · 09/05/2011 16:27

Seriously, a teacher would be annoyed that a child is interested and knows a bit beyond the curriculum?

LadyThumb · 09/05/2011 16:31

Wikipedia: In Euclidean plane geometry, a rectangle is any quadrilateral with four right angles.

DilysPrice · 09/05/2011 16:34

At what age does being proud of what you've learnt - in the context of a lesson in that subject - become showing off and something which must be discouraged at all costs for fear of losing popularity? Three? Five? Seven?

I wouldn't let the square thing lie either - this is basic mathematical knowledge, well within the capability of an 8 year old, and in the context of maths homework mathematical language should be used accurately.

Goblinchild · 09/05/2011 16:36

'My daughter still remembers the child in year 5 who interrupted the teacher who was explaining the three states of matter to shout 'there are four! there's plasma!' - at which the teacher broke off to say yes, fair point, there is plasma, but there won't be any plasma in the experiment we're doing in the classroom, so we need to focus on these three.....'

Exactly the same thing happened to me last year.
I gave them a merit for knowing something interesting, before I said 'However, we are focusing on these three this term'

At lunchtime, he and I had a chat about Non-Newtonain solids and fluids. Very interesting it was too. I love that sort of open-ended wondering about new ideas and knowledge.

Al0uiseG · 09/05/2011 16:38

Goosey How lovely to have such a bright enquiring son! Good job you know what you're talking about too, my poor kids have to wait for Dh to answer the Maths stuff. :o

WriterofDreams · 09/05/2011 16:41

The definition of a rectangle is a quadrilateral with four right angles. Therefore a square is, most definitely, a rectangle :)

FreudianSlipOnACrown · 09/05/2011 16:43

"Seriously, a teacher would be annoyed that a child is interested and knows a bit beyond the curriculum?"

Yes there are teachers like that. :(

I think your DS is very lucky to have you sticking up for him. You should point out that while you understand he didn't give the answer she wanted, he was NOT incorrect.

FreudianSlipOnACrown · 09/05/2011 16:47

"I love that sort of open-ended wondering about new ideas and knowledge."

Same here. That's what education should be, IMO, not just rote learning of exactly what the NC tells us.

ratspeaker · 09/05/2011 16:53

Even Wikipeadia states "a square is a rectangle as well as a rhombus"

en.wikipedia.org/wiki/Square_%28geometry%29

senua · 09/05/2011 16:54

Out of interest, Goosey, what was the 'correct' answer?

GemAimee · 09/05/2011 16:54

I can remember several occasions where I (politely and meekly) questioned my teachers. Some rewarded it. Some hated it.

Maybe I just had an annoying face. :-)

Your son was right. I think the teacher needs to know that.