# Teaching prisms to Y3

Discussion in 'Primary' started by roddywoomble, Feb 5, 2011.

1. ### roddywoombleNew commenter

Some advice please. I have to teach my new Y3 class (I'm on placement) about the properties of prisms. I had to get the information for what I would teach over the phone, which wasn't ideal, but was unavoidable. I know I need to teach from unit B2, so I know they will have had some experience of prisms in unit B1. The children need to visualise 2D and 3D shapes and be able to explain what a prism is and how it differs to a pyramid. They need to talk about vertices, faces and sides of the shape. Any advice would be welcome - I'm not sure on what to do for the activities part of the lesson as I'm not sure if the school has any 3D shapes for me to use. I'm thinking of beginning the lesson with the story of the little prism, who has two faces on each side of his 3D body. What do you guys think of this? Hopefully it will help them to remember what a prism is.
Thanks,
Shane

2. ### roddywoombleNew commenter

Some advice please. I have to teach my new Y3 class (I'm on placement) about the properties of prisms. I had to get the information for what I would teach over the phone, which wasn't ideal, but was unavoidable. I know I need to teach from unit B2, so I know they will have had some experience of prisms in unit B1. The children need to visualise 2D and 3D shapes and be able to explain what a prism is and how it differs to a pyramid. They need to talk about vertices, faces and sides of the shape. Any advice would be welcome - I'm not sure on what to do for the activities part of the lesson as I'm not sure if the school has any 3D shapes for me to use. I'm thinking of beginning the lesson with the story of the little prism, who has two faces on each side of his 3D body. What do you guys think of this? Hopefully it will help them to remember what a prism is.
Thanks,
Shane

3. ### forestjeNew commenter

Go and buy a large toblerone.I use this to explain what a prism is and then we all eat the chocolate afterwards.

4. ### wellie1970

How about making the 3D shapes out of plasticine, then slicing them up and examining the faces?
Eat the toblerone at home!!!
: ))))

5. ### alice.smith

hi shane, I am also on placement in a year three class and will be teaching this next week.

Toblerone box is a great idea.

I am also thinking of peeling a carrot down until it is a cuboid and chopping this in front of the class to show the identical cross sections.

use straws and blutack/plastercine to get children to construct their own prisms from your drawing.

i will also use this website in my main teaching as it has a great way of showing the prisms from all aspects; www.learner.org/interactives/geometry/3d_prisms.html

just some ideas

alice

6. ### bestprimaryteachingresources

Hi,
I've used the Toblerone idea and they always seem to remember it.
They need to be confident inunderstanding and using the correct vocab. (A finalist on The Apprentice with a first class honours degree didn't manage to get the prism shape correct!)
Take a look at these 3D resources which consolidate previous learning and have the following resources to aid the teaching of 3D shapes at KS2

Loop Game x 12 Cards

3D Poster

Labels x 14

Big Shapes x 7

Nets of: cube, cuboid, pentagonal prism, triangular prism, square-based pyramid and tetrahedron

Key Questions x 9

Title

Net Investigation

Display Border

Matching Activities

Sorting Activity

Properties of 3D Shape Worksheets

Power Point Presentation 3D Shapes

Using the resources from this product will enable you to create a
colourful shape display and will give you plenty of resources to aid you
in the teaching of 3D shapes.

It includes the shapes: cube, cuboid, sphere, cylinder, cone, various pyramids and prisms.
http://www.bestprimaryteachingresources.com/numeracy-resources/shape/3d-shape-key-stage-2

7. ### roddywoombleNew commenter

Wait...a solid cylinder isn't a prism? Whoops! I've taught my class that they are (i.e. a non-hollow cylinder) and haven't had anyone (class teacher or uni tutor) suggest otherwise. Even the textbook I used said that a solid cylinder was an example of a prism! I used the toblerone idea which was nice for showing them cutting across the cross-section. I also made up 'the story of the little prism' who is always sad because he has two identical faces on each side of his 3D body which can't see each other and will never meet. It worked really well. For the plenary they sorted 3D shapes into PE hoops as 'prisms' and 'not prisms.'

8. ### Andrew JeffreyNew commenter

Hi shanehurley - to the best of my knowledge this all hinges on the fact that a circle is not a polygon - it must have straight sides to qualify as such. Thus, as a prism is a polyhedron built on a polygon (which does not have to be regular, but must have straight sides) a cylinder cannot be a prism.

If you web search 'What is a prism?' you will probably get a much better explanation than that!

9. ### mystery10Occasional commenter

</td><td><table cellpadding="0" cellspacing="0"><tr><td align="left">Posted on Sunday, 02 November, 2003 - 02:51 pm: </td><td align="right"> </td></tr></table><hr /> Hello.

i
would like to know if the strict defintition of a prism is one where
the cross section MUST have straight sides or whether a cylinder could
be classed as a prism (one with infinite sides to the cross section). I
must admit that i have always considered a cylinder to be a prism but
according to my son's primary school teacher it is not! Who is right??
Many thanks.

Mark Bishop </td></tr>

<tr><td><a name="POST36350">[/URL]Philip Ellison
</td><td><table cellpadding="0" cellspacing="0"><tr><td align="left">Posted on Sunday, 02 November, 2003 - 03:43 pm: </td><td align="right"> </td></tr></table><hr />Strictly
speaking, a prism must have a polyhedral cross-section, so a cylinder
is not a prism. However, a cylinder can be thought of as the limiting
case as the number of sides of a prism tends to infinity, despite this
not being completely "correct".</td></tr>

<tr><td><a name="POST36352">[/URL]Mark Lobo
</td><td><table cellpadding="0" cellspacing="0"><tr><td align="left">Posted on Sunday, 02 November, 2003 - 04:17 pm: </td><td align="right"> </td></tr></table><hr /> here is what the thesaurus says

Mark</td></tr>

<tr><td><a name="POST36355">[/URL]Emma McCaughan
</td><td><table cellpadding="0" cellspacing="0"><tr><td align="left">Posted on Sunday, 02 November, 2003 - 05:40 pm: </td><td align="right"> </td></tr></table><hr /><font color="#119911">This
came up once before (but hasn't been archived yet), and we discovered
that the answer was different in different languages.

I think
the problem is that in English, we've always thought of prisms and
pyramids as types of polyhedra, and hence they have to have plane faces.

Apparently in other languages, this is not necessarily the case.

I
would much rather have a definition which allows for non-polygonal
cross-section (or base, for a pyramid) - it certainly simplifies
learning all those volume formulae if you can regard a cone as a pyramid
and a cylinder as a prism.</font></td></tr></table>

10. ### mystery10Occasional commenter

See thread above from nrich before you get so certain about whether or not a cylinder is a prism - there's a bit more to maths than meets the eye.
I shudder when I read primary maths text books which describe a circle as having one side - to me it is a polygon pushed to the limit. Draw a series of polygons - 5 sides, 10 sides, 50 sides, what does it start to look like - a circle.
This is much better thinking for a child and useful for higher level maths later on rather than the narrow right or wrong method that primary maths frequently employs. Much of primary maths makes the cleverer child feel dumb, as they would get the better mark by just swallowing useless and dubious facts rather than thinking about it.
My child was taught in Year 2 that a regular polygon had equal sides. When we talked about it home together and realised that it had to have equal sides and angles it put her in a very awkward situation with her homework as she wanted to get it right for the way the teacher had taught them, not right.
What would you advise a parent in this situation?

11. ### florapost

don't toblerone contain nuts? not a recommended course unless you are very certain of your pupils

12. ### florapost

don't get hung up on the tobleron - remember that's a 'triangular-based' or ''triangular' prism - and then there are all the others
and yes - if you want to send me to the staff room sobbing, describe a circle as having 'one side'
i would say a circle is the infinite limit of an n-sided regular polygon just as the infinite limit of 1/n is zero - but i wouldn't say it to Y3
but i really wouldn't call a cylinder a prism any more than i would call a circle a polygon until and unless i could introduce the above concept
BUT i probably would say to Y3 that the polygons at the end are connected by rectangles (i like this - it's one of the few ks1/2 occasions where 'rectangle' really does mean 'square or oblong') and this is inaccurate - a prism has its ends connected by parallelograms - if they are rectangles, it's a right prism, as opposed to being an obiquel one, - hmm - maybe i'd mention that in passing and see if the top group bit - even with my lot, i don't tend to waveoblique prisms at them till Y5
does your school have a decent set of 3D shapes including prisms with lots of different 'ends' - it can be interesting to set oout a group of prisms, pyramids, spheres etc and get them to picjk out the prisms - stars for the kids who realise cuboids and cubes are prisms
oh - and whoever it was - all sides equal, not all angles equal is 'equilateral' - only the triangle has to be regular if equilateral - i mutter something about inaccurate textbooks to excuse teachers - but in truth, teachers just ain't perfect and these things can slip through - i'm sure you can be tactful and accurate at the same time !!

13. ### florapost

'fascinating, isn't it, how much there is to maths' goes a long way with a small child

14. ### mystery10Occasional commenter

I did try to be tactful and accurate about the business of regular polygons having to have equal angles and equal sides, but my child was moved down a maths group shortly after so maybe the point was not taken well!!

15. ### gillkirby1

What a great idea. I've always wondered why a cylinder is not a prism. Lots of adults get this wrong too!

16. ### iamagoodgirl

A prism has both ends identical and its side faces are rectanglar