Weather: Fill the cup with water. Put shaving cream on top for a cloud. Explain that when clouds get really heavy with water, it rains! Then put blue food coloring on top of the cloud, and watch it rain. Just in time or my weather unit this week! I thought this was a really cool experiment that I must do with my students to introduce a weather topic or even the water cycle! - Oh my trendy!
Great science activity for Early Years or Year 1, have a look at this Blog for more details. Which materials will stop Humpty Dumpty breaking when he falls off the wall? Lots of opportunities for prediction and discussion