I read that:
Take a cupful of water in a beaker and add a few drops of dilute sulfuric acid. Heat the water. When it starts boiling add copper sulfate powder slowly while stirring continuously. Continue adding copper sulfate powder till no more powder can be dissolved. Filter the solution. Allow it to cool. Do not disturb the solution when it is cooling. Look at the solution after some time. Can you see the crystals of copper sulfate? If not, wait for some more time.
So why is sulfuric acid required in this experiment?