Charges are actually present on every object but the positives cancel the negatives so the object is neutral. Lay the soda can on its side on the table. Charge the golf tube and bring it near the soda can. Record your observations. Note that the soda can is made of metal, not plastic as all of the rods are.
Metals behave a little bit differently.
Charges are free to move around in a metal object. Here is the time to find out how the golf tube attracts hair and pieces of paper. Take a rod, charge it and bring it near the hanging rod. Leave the uncharged rod hanging. Take the other type of rod and bring it near the hanging rod.