Well there a Newtions cradle shows concervation of momentum well- http://en.wikipedia.org/wiki/Newton%27s_cradle The little balls that clink off each other. The kind of thing you would find on the desk of an 80s bisiness man. I guess this is a tricky one to make though.
Hmm what else. Maybe you could get two little cars (your teacher may have suitable ones. Have one sitting still and push the other one towards it from behind and let it go. If you put plenty of blu tak on the cars hopefully they will stick together and move off together. This will double the mass and half the speed (under ideal conditions)
I hope I’m not asked to teach that as I think I would be rubbish at that subject… but I love teaching, especially about the brain! I like using hands on activities and interactive quiz to get people thinking about the topic. Do you think you would pay attention if I tried to teach your class for a lesson about the brain? What makes you excited in a lesson?
I’m going to answer this as an athlete, not a scientist. How about you put some people on roller skates? In roller derby, the sport I play, we are constantly talking about conserving or losing momentum, because a big part of the game is that the blockers hit the jammers to keep them from getting through and scoring points. Jammers need to evade these hits as much as possible so as to not lose momentum. We also have a move called a “whip” where you steal the momentum of another player, by grabbing their hips and pulling on them to go past, or grabbing their arm and having them pull you by (obviously, this is something you would do to help a jammer from your own team only!).
But I digress… obviously I am crazy about this sport! 🙂
@lukealanpatrick @Jamie ‘s suggestion of the Newton’s cradle is definitely the simplest demonstration. The Law of Conservation of Momentum basically says that if a moving object is suddenly stopped, its kinetic energy has to go somewhere.
It’s a shame you’re not allowed to take the demonstration to a fairground. Dodgems/bumper cars would have been the perfect example 😉
Good luck with your presentation. Let us know how it goes.