Hi Lizzie. To create a spark you need the help of friction. Try rubbing your hands together quickly for 5 seconds. Your dry hands moving over one another creates heat, caused by friction. There is what we call resistance, it takes your energy and effort to rub your hands together. Much in the same way when rocks hit each other. When a rock hits another rock, the energy of the blow turns into the heat of friction. And this heat incredibly melts the rocks. Then very teeny tiny pieces of melted rock break off. How neat is it that sparks are molten rock!

Not all rocks will create a spark. You need a hard rock like flint. Soft rocks break apart before creating a spark!