This week my first year classes have been learning about change of state and I was thinking of doing a quick practical boiling water in a kettle and measuring the specific latent heat of fusion of water. The aim of the practical was to reinforce the theory since the class had already used temperature sensors etc. so didn't really need further practice. Is it worth getting out all the apparatus for a 3 minute practical? I decided not, so did it as a demo. The advantage of a demo is that it's much faster, more likely to work (but far from guaranteed) and everyone gets the same data to process making class discussion easier to follow. I think the outcome was good, the point about the temperature staying the same was clearly made and we managed to make some sense of the too low value for the latent heat.