For some time I've been thinking of practicals that can be done in the Engineering option, particularly related to rotational dynamics. I've got two PASCO rotational systems so I'm OK but what if you don't have one of these rather expensive babies? You can do some nice stuff if you've got a rotational motion sensor but they're not cheap either. I tried to make something with meccano but it didn't work well. I then tried applying a torque to a drinking straw with an elastic band motor but it wasn't stable. I tried attaching different things to a battery powered drill but the results weren't consistent. When all else fails simulate. It worked very well in Algodoo. See if you can work out why the acceleration decreases towards the end.