The reactivity order of metals towards water is:

Sodium and potassium react violently with the release of huge amount of heat. So the reaction is highly exothermic. Hydrogen gas which is produced during the reaction catches fire. Calcium reacts less violently with water. The heat evolved is not sufficient for the hydrogen to catch fire. Instead, calcium floats over water because bubbles of hydrogen gas stick to the metal surface Aluminium, iron and zinc react with steam to form respective oxide and hydrogen gas. Thus, metals react with water to form metal hydroxide and hydrogen gas, which we can check by placing a match-stick near it. The order of reactivity with water in descending order.