1)     Pour cooking oil into the bowl until it is about 1/3rd full.

2)     Place the oil on the stove element and turn the element to LOW.

3)     Add a few drops of food colouring to the oil.  Watch what happens.

Explanation: Convection is the transfer of heat throughout a fluid (either a liquid or a gas) by the movement of molecules. As the fluid warms up, its molecules move faster and spread further apart, becoming less dense. This causes them to rise. In this experiment, this causes the cooler particles of fluid to be forced down towards the bottom of the bowl, where they are then warmed and begin to rise. The food colouring helps to track this motion.

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