Which type of chocolate melts the quickest? Science experiment

As part of the ‘States of Matter’ science topic for Year 4.
Here is the powerpoint for the an experiment on which chocolate melts the fastest. Included are visuals, explanations and details of the experiment.

You will need:
cake tray to a cube of chocolate into.
1 small square of white chocolate, milk chocolate and dark chocolate.
kettle to boil water
tray

THE EXPERIMENT:
Place one square of chocolate in each cake section of the cake tray.
Place the cake tray inside a tray.
Boil the kettle and pour the water into the tray.
Watch the chocolate melt.
Which one turned into a liquid the quickest?
Place the tray outside and see that it hardens back into a different shape