Pouring milk on your oatmeal physical change.
Physical change describes a change in the matter while a chemical change is a process at which a particular object becomes a new substance. Some of the examples of physical change include boiling, freezing, melting, etc.
In the case of the oatmeal, adding milk turns it from a solid state to a liquid state. Examples of a chemical reaction include burning wood since the final product will be ash, the reaction between an acid and a base, milk turning sour, and etc.
