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

[GooseyLoosey]

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).

thanks, I think that's the answer I was groping towards! (At least I knew a square was a rectangle, though.)

A square is a rectangle is a parallelogram is a trapezium is a quadrilateral etc-each is a more tightly defined subset of the other. I did that in Yr7. Part of mathematics teaching is to introduce children to more precise definitions of disclipline-specific vocabulary, and that is actually fairly woeful from anyone, yet alone a maths co-ordinator.

But I suspect the problem from the teacher's point of view is gauging whether your son has understood what distinguishes a rectange from a square, which is important even if this answer is technically correct. But he/she should have asked, not assumed. Equally, I wouldn't assume your son is engaging in the semantic exactitude of posters here either.

I do remember at school suddenly changing from oblong to rectangle - I can't remember when, but it was suddenly "decided" that oblong was the childish way to say rectangle.
(althought I'm pretty sure we were also taught at that time that it was an irregular rectangle adn the sqaure was regular)

Have been lurking on this thread. Would love to know how explaining it to the teacher went!

OK - back to recount how the explanation went. I should first mention that ds is not the most subtle soul (which the school are aware of) and tact is a foreign land to him.

DS: "On my homework, you said a square was not a rectangle. It is, a rectangle has 4 right angles and parallel sides of equal length".

Teacher: "Yes, but it must have sides of 2 different lengths".

DS: "No - opposite sides must be of equal length, but all the sides can be of the same length. A square is a type of rectangle [produces definition printed from internet at this point]."

Teacher: "Well I meant you to draw a shape with sides of unequal length"

DS: "But it didn't say that, so I wasn't wrong was I?"

Teacher "OK, I agree, you weren't wrong" (and she gave him an extra star for his work so ds is happy).

Oh good! :o

She clearly didn't know though!

great result!

well done DS!

A SQUARE IS A RECTANGLE WAAAAHHHH

oh, and a square standing on it's corner is still a flippin' square not a diamond....

Sounds like she took it fairly well... Always correct the teacher when necessary!

I really don't like using the word 'diamond' as a mathematical term.

I have read through most, but not all, of this thread. And I really love it when maths becomes a topic for popular discussion, hats off to MNers!

Now, back to 'diamonds', I think most people would conjure up an image of a rhombus (Factoid: it's called a rhomboid in the US). But they would also picture it standing upon one of it's vertices. IME people are much less likely to identify the same shape as a diamond if it lies on its side.

I am a primary school teacher (12 years) and yes I also agree. A rectangle can most certainly be a square. 4 right angles and 2 pairs of opposite and equal sides. Job done.

I would explain this to the teacher and also explain that it is important to admit when you are wrong. I learn things from my small ones all the time and we learn together in my classroom. I pride myself on the fact that my pupils can and do contribute their ideas, knowledge and skills. (I could obviously go on but I think the teacher in this case should 'man up' and eat some humble pie)

Hurrah! Well done goosey and gosling :)

Hurray for Goosey's DS!

well done, ds! (And well done to the teacher, in the end - glad ds got his star.)

Really glad you posted this update Goosey, and fair play to the teacher for agreeing he was right and that he could have an extra star. Everyone gets things wrong and it's nice she acknowledged his extra efforts rather than keep arguing her (wrong) corner!