Feel metal rods before and after they have been dipped in hot water. Discuss heat (thermal energy) transfer in terms of molecule motion.
Science content (2016 curriculum):
Chemistry: Atoms, Molecules (3-7)
Physics: Heat (3)
Physics: Energy forms, Conservation of Energy (1, 3, 4, 5)
Science topic (2005 curriculum connection):
Physical Science: Properties of Matter (grade 2)
Physical Science: Chemistry (grade 7)