ELI5: Explain Like I'm 5

Conservation of mass

Conservation of mass means that matter can't be created or destroyed. This means that if you put together the same amount of material, like clay, no matter what shape it is made into, the total amount of clay will always be the same. So if you start with a lump of clay, and shape it into a flower, the flower still has the same amount of clay as the lump you started with.If you break the flower apart, you'll have the same amount of clay you started with. Conservation of mass is like a puzzle, where the same pieces are always there, just shaped different ways.