A slightly new iteration of a classic science toy. Variously called a vortex or cyclone, this includes the twist-on connector that allows you to pair two liter (or other sized) water bottles. Spin to create the swirling "cyclone" and watch as the water moves rhythmically to the lower chamber (bottle). The turn it upside down and repeat. Like a lot. Add color and/or sparkles to make the effect more dramatic! Ages 4+