4.6 recall that energy transfer may take place by conduction, convection and radiation Task 1
· Try the animation: particle model - conduction
· Extension: what is the limitation of this animation? (Check your answer with the Heating a Solid animation) The limitation is that the animation does not show that the object expands when it is heated.
Task 2
· Try the quiz on the Cooking animation
· Extension: what's the mistake in the description of convection? The animation states that the molecules at the bottom of the liquid heat up and they start to rise, when they cool down the molecules shrink again and sink. This creates a convection current and gradually all of the liquid heats up. This is wrong because if you heat a liquid from below, the liquid at the bottom gets heated up and it expands. The liquid then rises because it has a lower density, afterwards the cool liquid (at the top) sinks to the bottom where the heat source is and it then expands and rises. The process is repeated. This is called convection current. 
· Try the animation: particle model - conduction
· Extension: what is the limitation of this animation? (Check your answer with the Heating a Solid animation) The limitation is that the animation does not show that the object expands when it is heated.
Task 2
· Try the quiz on the Cooking animation
· Extension: what's the mistake in the description of convection? The animation states that the molecules at the bottom of the liquid heat up and they start to rise, when they cool down the molecules shrink again and sink. This creates a convection current and gradually all of the liquid heats up. This is wrong because if you heat a liquid from below, the liquid at the bottom gets heated up and it expands. The liquid then rises because it has a lower density, afterwards the cool liquid (at the top) sinks to the bottom where the heat source is and it then expands and rises. The process is repeated. This is called convection current.
