A telephone

MATERIALS:
- Two plastic glasses
- 6 - 8 m. of fishing line
- 2 clips
- a cutter


INSTRUCTIONS:
- Make a hole on the bottom of the plastic glasses.  
- Put one end of the fishing line into the hole.
- Make a knot to a clip. Do the same with the other end.
- Tighten the fishing line and talk to a friend.


WHY?:
The  sound travels better through a solid (fishing line) than the air.

Lung capacity

MATERIALS:
- A tank
- A tube
- A plastic bottle with capacity measures
- Water

INSTRUCTIONS:
- Fill the tank with water.
- Fill the bottle with water and put the tube in it.
- Put the bottle upside down in the tank.
- Fill your lungs and blow in the tube.
- Look at your lung capacity in the bottle.

WHY?
You fill your lungs as much as you can and  when you blow through the tube, all this air goes into the bottle and expels the water in the bottle, it occupies its place.

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The candle goes out

MATERIALS:
- A candle
- A plate
- A glass
- Matches or a lighter
- Water


INSTRUCTIONS:
- Place the candle on the plate.
- Pour some water into the plate.
- Light the candle.
- Put the glass upside down on the plate.
- Look at the flame and the water in the glass.


The flame goes out and the water level in the glass rises.


WHY?
The candle flame heats the air in the glass, and this hot air expands. Some of this hot air escapes out from under the glass  (you can see some bubbles). When the flame goes out, the air in the glass cools and contracts. The cool air inside of the glass creates a vacuum due to the low pressure inside the glass and the high pressure outside of the glass. 



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