Quite well explained and demonstrated:

http://www.youtube.com/watch?v=D_i3PJIYtuY&feature=related

A cartoon - good intro..found by student :)

http://www.youtube.com/watch?v=9T7tGosXM58

This site has loads of these - but they're also linked to a huge variety of other sites - the ones I've just played with are to do with Unit 4 (quelle surprise!) However I also looked at robots - to link with U2 and then of course there will be something about inventions too.... Hope you enjoy it too :) Sange

This is a test on my part, to see if I cana do this!?!?!? Also chose to share this powerpoint, found under advanced search option in google. This has helped us to find suitable info about other materials too; especially plastics :)