# how do you explain the difference between 3D and 2D shapes to children

Discussion in 'Early Years' started by tinyears, Jan 22, 2008.

as above

2. ### tinyears

as above

We talk about 2D shapes being flat (hands together) and 3D shapes being fat (hands wide apart).

I introduced 3d shapes by "blowing up" 2d shapes in my magic bag. See the link below for an explanation:

Of course, the problem with the plastic 2d shapes that we all use at school for sorting etc, is that they are really very thin 3d shapes. I'm not sure how you get around that problem.

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5. ### julia pearl

We look at 3D shapes and call them '3D shapes' and then ask what the difference is between 3D and Flat (as others have said).

Then we look for all the 2D shapes in 3D shapes eg cylinder = 2 circles + rectangle .. they could be 'open' so no circles!!

We do 'Transformation of Shape' activities ie "Change this rectangle piece of card into a 3D cylinder" etc via problem solving activities. Through transformation (hands-on) the kids seem to get the idea. The more you practice, the more they get it!!

6. ### debbiehep

This is one of my 'bugbears'.

I don't believe we should use 'flats' to teach 2D shape at all.

Flats ARE 3D shapes and it is totally flawed to use them to teach 2D shape and the name of 2D shapes.

Why don't we just stick to what is correct in the first place?

You can easily use resources which have 'drawn' 2D shapes on. You can explain easily that we can hold 3D shapes - that they are solid.

You can talk about 'faces' and 'edges' at an early stage and use terms like the cylinder has two 'cicular' faces and so on.

You can show that you can hold the paper or card that the 2D shapes are drawn on but that you cannot hold the 2D shapes themselves.

You can show that flats are not flat at all because if you make a pile of them, they have height.

It is the easiest thing in the world to teach 2D and 3D shape when they are taught together so that you can point out the differences in meaning and definition.

It is just a mess when we try to use flats and other 3D shapes to teach the names and understanding of 2D shapes.

But - to try this idea out of 'correctness', you have to be prepared to disregard some of the resources and guidance that exists already.

However, don't I always encourage teachers to be discerning, thinking, challenging and brave?

Go for it.

7. ### debbiehep

'cicular' - try "circular"!

This is one of my bugbears too.
I was told that I was "getting philosophical" when I pointed out that the circle I had drawn on a sheet of paperwas 2D because it didn't exist on the other side.

I think the teacher who said this browses this site. I'd like to reassure her that I have the greatest respect for her talent and subject knowledge...

But I think I'm right on this.

We can all do one thing right from the start by using the word face. Little ones accept that word with no problem, so we can use it fearlessly.

10. ### MszEstablished commenter

I say 2D shapes are like the ones we draw but can't really hold in our hands and 3D are the solid ones we can hold.

11. ### mystery10Occasional commenter

I wonder if you explore interactive white board resources for 2D and 3D shapes at secondary level you will find something that illustrates your points nicely? Sorry not to be more specific than this but I think there's probably something on mymaths etc that would do the job nicely.
Also while you are at it, my other bugbear is talking about circles having one curved side. With an interactive white board resource you can show so nicely how if you draw a regular polygon and keep on increasing the number if sides you get closer and closer to a circle.

Oh, infinity...

I like to use the wonderful bit in Joyce's Portrait of an Artist as a Young Man in which eternity is described by a priest in terms of a bird taking a grain of sand and building a mountain...and thebn...

...but with older children, of course..

Mystery10, I wonder why you're so worried when you're clearly doing everything yoiu can for your daughter.

And I can't resist pointing out that you;ve used the word nicely three times in your post. Do you think we're all duffers?

i'd love you all to read the book but know that time takes it toll.

I was going to explain this but am currently so downhearted by the fact that the "superhighways" haven't increased general knowledge despite all the hype.

14. ### T34Established commenter

never mind "what is a 2D shape or what is a 3D shape".
What is a "shape"?
Let's start at the beginning, before irreconcilable contradictions have been embedded.

15. ### MszEstablished commenter

are we going with shape is the form of an object?

16. ### Rach63

I agree with debbie - this is a bugbear. But where do you stop??
So many concepts are (initially) incorrectly formed at this young age - some are refined and altered, others remain fixed until adulthood.
Weight /mass? , most of my staff talk about the scales for weighing, but many of them are actually just pan-balances, a ruler is really a rule.... The list is endless!!!! Anyway - I tell my children that 3D shapes are solid and that means you can pick them up or wrap your hands round them. Some children sometimes point out that you can do this with flat shapes - if they are intelligent enough to realise that, then I go on to explain that they actually are 3D.
As a previous poster implied- in EYFS it's just as important to be matching, comparing, pointing out shapes (without necessarily naming) Learning about corners, sides, faces, edges I'm in pre-school though...

I'm interested in this one as a maths teacher / reception parent, occasionally seeing things that might explain later problems. I tend to agree about the plastic "2D" shapes - and interactive whiteboards give a good kinaesthetic way of exploring genuinely 2D shapes.
My daughter started using a ruler, and explained to me that you start drawing the line from 1 on the ruler. Might be sensible advice when drawing with one of those rulers that starts directly at 0, but probably feeds into the problem of measuring from 1 instead of 0.
The word rhombus got replaced in her vocabulary by diamond, whilst at pre-school. (I don't mind her knowing the word diamond, but it did seem to replace rhombus - I suspect somebody must have said "no, it's a diamond", as two words for the same thing isn't usually a problem for her.)

Cariadlet and I were chatting about 2d and 3d shapes the other day. We eventually decided that even when you draw a shape it is really 3d, it's just that the thickness is so tiny you can't see it with the naked eye. But there must be some height to a drawn shape - otherwise pencils wouldn't get shorter and shorter the more you use them. That led us onto deciding that the only truly 2d shapes must be imaginary ones that you picture in your head (we hadn't thought about the IWB).
Mind you Cariadlet is 8 - I don't think I'd have that conversation in my Reception classroom.

19. ### daybyday

You can get a set of 3D shapes that are hollow and have one face missing so that you can stuff a piece of material in there and pull it out like a magician. They are also very useful in the sand and water tray as the children can contrast the cube that fills up with water versus the square that you can hold in your hand but will not fill up no matter how much you pour.

20. ### MszEstablished commenter

I tell my Y2s that 2D shapes have height and width but no depth but I'm not sure reception have the concept of height , width or depth to understand and really they just need lots of experience of handling 3D shapes and developing that understanding