Most annoying practical
When I started teaching I used to spend half my time trying to get the class to be quite now I find myself encouraging them to make noise. Today my HL class did the sliding whistle practical, probably the IB's loudest physics experiment. I say "physics" here as chemistry certainly has some louder bangs. It's actually quite unpleasant being surrounded shrill whistles for an hour and I've devised an alternative with drinking straws that makes much less noise, however the students didn't go for it and chose the maximum disturbance method. One problem is that with all the whistles being blown at different times you're likely to record not only your own whistle but also your neighbours,making the frequency spectrum quite complicated. One group decided to reduce their experimental errors by doing the experiment in the disabled toilet however the biology class, which is next door to the toilet, were doing a test so they had to move to the chemistry lab where they got great results.