A student makes observations when water is added to a blue solution of copper sulfate. The student makes only 1 observation: the solution changes to a lighter shade of blue. Is this an example of a chemical reaction? Explain your reasoning.

No, I believe this is not an example of a chemical reaction. What we actually see here is a physical change of the solution. Since we are adding more water to an aqueous solution which is also made up mostly of water, what we are simply basically doing is dilution. Since the solution is being diluted, so definitely the color turned lighter.