Photograph water droplets that are falling down and hit something! This exercise is a lot of fun and can be done with a group of children during the winter break. I use one strobe light starting at at f8, 1/200sec. ISO 100. Try the setting that works best for you.
I used a cooking bowl and I hung a freezer bag filled with some water (you don’t need a full bag, it is too heavy) over the bowl. Then I poked a small hole into it. I started the strobe unit in a 90 degree angle and tried a few shot. It took a little bit of patients but after a while I got some quite interesting images.