To prove that air supports burning, let's take two lighted candles.

1) Put one candle in a tumbler containing water and cover it with an inverted glass.

2) Put the second candle in open air. After some time, this covered candle gets extinguished and

3) After some time, this covered candle gets extinguished and the water level rises up in the glass.

4) This happens because oxygen present inside the air in the glass was used up completely.

This experiment shows that air is necessary for burning.

Practical life example:

In villages, the food is cooked on chulha. In the chulha , blowing air helps in quickly burning the wood in it. This also shows that air supports burning.