Air pressure Experiment 9th grade

The following video clip demonstrates that air has weight. We have probably all tried the experiment with a cup covering a candle. The candle will go out, because when the cup isolates the candle from the oxygen that the candle needs to burn, the candle will burn out the oxygen left in the cup.

However, if we do a variation of this experiment by puting the candle in a bowl containing a small amount of water, we will find that the water will get sucked into the cup, as the candle burns. When the candle burns the oxygen in the cup, the air pressure decreases. When the air pressure outside the cup is stronger then the air pressure inside the cup, the water is pushed into the cup by the air pressure.