Balloon rockets! Easy fun activity for kids! I love the educational aspect of the experiment as well! You can explain how real rockets work by exploding fuel inside a chamber that is open at the bottom. The force of the explosion creates an opposite force that pushes the rocket up and into space. Cool!
Fill your ice cube trays with water, adding a drop of food coloring to each section. When frozen, these can be popped out and put in bath water. They’ll have fun “chasing” them around in the tub and trying to grab them before they melt.