A Diving Octopus and a Water Tornado

We are learning about the water cycle, clouds and tornadoes.

Teacher had a tornado bottle.

We enjoyed swirling it and watching the tornado suck air up into its centre while letting water spill out along the edges of the tornado.  We used a timer to see whether water spilled out more quickly if left alone or as a tornado.  The tornado won!

We also had another water puzzle:   Teacher put an octopus into a bottle of water. (She also made a similar fish from a pen cap, blue tack, a paper clip and an elastic band.)  She wanted us to think of a way to get the octopus or fish to sit at the bottom of the bottle, but then to come to the top again when we want.  We  tried turning the bottle upside down, tilting the bottle, shaking the bottle, opening the top of the bottle, blowing on the octopus and taking out the air in the bottle.  Nothing seems to work.  We had our thinking caps on for a long time before we hit on the solution…..squeeze the bottle.  This forces the air in the head of the octopus to compress, water rushes in and the octopus becomes heavier and sinks.  When you stop squeezing the bottle the air in the head of the octopus decompresses pushing the water out and the lighter octopus rising to the top again.  Easy and fun to make at home too!

At home: Make a Submarine

Pierce a hole in the lid and bottom of a plastic bottle.  Push a plastic tube through the hole in the lid.  Put your finger over the hole in the bottom. In the bathtub fill the bottle to the top with water.  Screw on the lid.  Let the bottle sink to the bottom of the bath.  Take your finger away from the hole and blow into the tube.  Your mini-sub will rise to the surface.  This is the principle on which submarines work.