Watch this video and follow the step by step instructions.
Wind is the movement of air near Earth’s surface. Changes in the temperature of air, land, and water cause wind. When air flows over a warm surface, it heats up and rises. This leaves room for cooler air to flow in. The flowing air is wind.
Air from a high pressure area will move towards an area of low pressure. High winds are caused when air moves between areas with large differences in air pressure.
What is happening?
The lit incense causes the the air at the bottom part of the box to be heated up. This creates a difference in air pressure. When the cardboard roll is in position, a wind tunnel is created. It provides a passage for wind to travel. The candle flame "dances" as wind escapes through the cardboard roll.