The law of conservation of mass states that in a chemical reaction mass is neither created nor destroyed. For example, the carbon atom in coal becomes carbon dioxide when it is burned. The carbon atom changes from a solid structure to a gas but its mass does not change. Similarly, the law of conservation of energy states that the amount of energy is neither created nor destroyed. For example, when you roll a toy car down a ramp and it hits a wall, the energy is transferred from kinetic energy to potential energy.
Teach about the conservation of energy and mass with these classroom resources.