In a Flush
In a Flush
Get flushing with Nina's mini-cistern and float!
What to do:
You will need a grown-up to help you make this invention. First you need to ask your helper to carefully cut approximately a fifth off the bottom of the plastic bottle. Next ask them to carefully pierce a hole through the middle of the ball, using a skewer or a similar sharp utensil.
Then cut a piece off the straw, just below the flexible part. Ask your grown-up to carefully make a small hole, the width of the straw, in the top curved part of the empty bottle. Squeeze the straw into the hole in the bottle.
Thread the polystyrene ball onto the end of the straw, inside the bottle. This can be fiddly so take your time. It’s important that you leave one or two centimetres of straw poking out the top of the ball. Hold the bottle upside down and check that the straw moves up and down, like a toilet handle, with the ball on the end. Well done, inventors, you’ve created your cistern! Now you need to try it out. Ask an adult to fill a bucket with water. The water level should be higher than the end of the straw but not as high as the top of the bottle. Make sure the bottle top is screwed on and place the ‘cistern’ and float in the water. The bottle ‘cistern’ will fill with water through the straw and the ball will rise. When there’s enough water in the ‘cistern’ the float will rise up and make the straw bend: this will stop any more water getting in. To ‘flush’ gently unscrew the bottle top and watch as the water flushes away, and the ball descends. Well done inventors!
You will need:
- An empty 1 Litre plastic bottle
- A small polystyrene ball (about 8cm in diameter)
- A pair of scissors
- A straw
Remember to ask a Grown-up for help.