Summary 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 Chemistry: Atoms, Molecules (3-7) Physics: Heat (3) Physics: Energy forms, Conservation of Energy (1, 3, 4, 5) Lessons activity is in Heat conduction Materials copper rods, several for a class, approx. 30cm long, or other metal that conducts heat well kettle of recently boiled water Procedure Space the metal rods out around the circle of students, and ask the students to touch a metal rod and feel how warm it is. (You may need to ask them not to hold them as warmth from their hand heats up the rod.) Gather up the rods, briefly dip them in the kettle of recently boiled hot water, then lay out again. Ask the students to briefly (copper metal heats up very fast) touch the end that was in the water. Students may also explore and feel the end of the rod that was not in the water, and the centre of the rod, and notice differences along the rod. They may also notice that after a short while, the whole rod will cool down again. Discuss what is happening in terms of heat: The molecules of water moved around faster as they were heated up. (Video of molecule movement in a liquid as it is heated: http://www.middleschoolchemistry.com/multimedia/chapter1/lesson2.) These faster moving water molecules transfer energy to the metal rod where they are touching. The energy from the hot water makes the molecules of the metal rod move faster, which we can feel as the rod heating up. The heat spreads up the rod as the faster molecules at the end of the rod bump into adjacent molecules and give them energy too - so the middle of the rod (even though it was not touching the water) got warmer as well. Eventually the molecules lose their heat energy to the air and the rod cools down again. The movement of heat when molecules transfer energy between each other by colliding with each other is called “conduction”. Notes ingridscience afterschool used a large copper rod in a campfire to feel conduction Grades taught Gr 2 Gr 3 Gr 5
