A clear case

Put spoons made of steel, silver, and plastic and a glass rod into a glass. Fix a dry pea at the same height on each handle with a dab of butter. 

In which order will the peas fall if you pour boiling water into the glass?

The butter on the silver spoon melts very quickly and releases its pea first. 

The peas from the steel spoon and the glass rod fall later, while that on the plastic spoon does not move. Silver is by far the best conductor of heat, while plastic is a very poor conductor, which is why saucepans, for example, often have plastic handles.