My show this year will touch on Relativity, Special as well as General. How can I explain both in simple (primary school level) language? Also maybe a short description on the difference between the two.
So please, the teachers out there, a lesson plan?
I think relatively few people can understand relativity in any terms whatever. I certainly don’t. For primary school level, perhaps a better idea might be to just touch upon some of the counter-intuitive and mind bending implications, such as time dilation.
Here’s a collection of videos made specially for kids that you could use to get you started. Many more resources are indicated by Google if you have the time to go through them. A long time ago, I had a book called Readable Relativity by Clement Durell which explains special relativity in very accessible terms without trivialising it or complicating it with technical jargon. The book assumes a basic knowledge of geometry, algebra and trigonometry, and so might be suitable only for the later school grades.
'Luthon64
Thanks. It must be very short. My aim is not to teach them the theory, more an introduction to it.
If only there was a site that you could go to and look up stuff 
Thanks. Problem is, like I said, how to say it in a few sentences and at primary school level. My target market is the old model c primary schools. I work at high schools as well, but it is quite difficult to get an appointment there.
just create enquiring minds and they will start looking for the answers to riddles etc. I would tell them how long light takes to travel from the nearest star (not the sun) and the speed at which it travels…then i’d boggle their minds about looking back in the past! some will run to mommy and tell them they saw the past!! then get a klap for believing shit!
Well Let me have a crack at it. (So we talking about a paragraph here?)
Between 1905 and 1915 Albert Einstein developed the theory of General relativity. In General relativity Space and time can be thought as one thing and that Mass acts upon it.
Think of a bed sheet being stretched out as space-time and a bowling ball lying upon it, bending the space-time around it. Why is it theory useful? It gives us a clue to how mass and gravity work in space times, and helped us learn that there are things like black holes.
The second theory of Albert Einstein is special relativity, and they key to it is understanding that no matter how fast you are moving you will always measure the speed of light at the same speed, and for this to be possible it means that the faster you are moving the slower your measurement of time is going to be. It may sound strange but with out General Relativity and special relativity things like GPS won’t work that is because the satellites that give us GPS work on clocks. And the clocks on the satellites run at different speeds that the ones here on earth and we have to keep adjusting the clocks on these satellites so that GPS works properly.
It may be useful and entertaining to set up[ this sheet thing for real, perhaps on a collapsible frame that is easy to transport, and then show them how a weight will make a dent in it, and how a marble rolled across the sheet will be affected.
Here is an interesting application of relativity. The short video on the page below explains gravitational lensing, and how it helps astronomers to see ancient galaxies that would otherwise be beyond visual reach.