Effect of room temperature on the burn-rate of a candle burns
The hypothesis that a candle in a colder room will burn more gradually/slowly is disproved. All of the candles burned at almost the same rate regardless of the surrounding temperature.
This science fair project can also be varied to compare the burn rate of candles made from different materials like soy wax or animal fat.
Try to repeat the experiment to compare the weight of the candle instead of the length. Would there be a difference?
What if the room temperature were to be varied more significantly? Eg. Measuring burn-rate at 5 degrees, 20 degrees and 40 degrees?
Candle - http://en.wikipedia.org/wiki/Candle
How does a candle work? - http://home.howstuffworks.com/question267.htm
Take the necessary precautions when handling fire. Ensure that no flammable materials are placed near the candles during the experiment. Adult supervision required.