A favourite end of term activity with Physics teachers at this time of year is to get classes to calculate how fast Santa would have to go to deliver all the presents in one night. The idea is to show how many laws of Physics would have to be broken. Those of you who don't believe might want to follow Santa's progress tonight on the North American air defence radar system
http://www.noradsanta.org/ They've been following him since 1958. It is s system normally used to track enemy missiles!