This is a good discrepit event to start a conversation on heat energy. Ice cubes are placed on blocks made of different materials (although students aren't aware of that). One ice cube melts at a much faster rate than the other. The block that melted the ice cube faster feels colder than the other. Students are quick to predict/assume that the warmer block would have melted the ice cube faster. This leads to a critical thinking discussion of how heat energy flows and the ability of materials to conduct heat better or worse than others.