In this fun science experiment you can make your own scuba diver in a bottle and learn about water pressure and density at the same time!

You will need:

• Thick tin foil (eg. a tin foil tray)
• Scissors
• Plasticine
• A Straw
• A paperclip
• A 2L Bottle

Method:

• Cut out a diver shape about 1.5 inches tall, wide enough to fit in the neck of the bottle.
• Cut the straw so there is a straight piece around 2cm long either side of the bendy piece.
• Insert one end of the paper clip to one end of the straw, then place the other end of the paperclip into the other end of the straw.
• Attach the paperclip onto the diver cut out so it looks like scuba gear!
• Place some modelling clay on the diver’s feet.
• Make sure your diver floats by placing it in a glass of water. If it sinks then there may be a hole in thestraw.
• Fill the 2L bottle right to the top (if it isn’t full it won’t work) and place the diver inside!
• Screw on the lid and squeeze the bottle – watch your diver move up and down as you squeeze and release the bottle!

The Science Bit:

Squeezing the bottle makes the diver more dense by forcing water up into the straw, as well as compressing the air in the straw as well. When the diver becomes more dense than the water it starts to sink, until the pressure is released. When you stop squeezing the bottle, the pressure releases and the diver becomes less dense than the water and floats back up. Check out the video below to see what should happen! [embedyt] https://www.youtube.com/watch?v=oA8Mj21sCsY[/embedyt]