The answers that apply are;
- rice moving in a pot of water that is being heated
- a radiator that emits warm air and draws in cool air a
- hot air balloon rising and falling in the atmosphere
Convection currents involve the transfer of heat in fluids (such as air and liquids). Since they are not good conductors of heat, when they are heated the layers being heated (especially from below) becomes hot and less dense, These layers begin to rise while the cooler layers above begin to sink and replace the rising hot less dense layers. This cycle continues in a loop to form conventional currents.