Prepare the quarter by rubbing it with fine steel wool, then washing with detergent. Rinse thoroughly. Wear rubber gloves to avoid touching the quarter with your bare hands once it has been cleaned -- oils from your fingers will interfere with the plating process.
Wrap the quarter in a few strands of thin copper wire so that it is able to hang freely. The wire will make it easier to lift the coin out of the solution when the plating is complete.
Place the copper strip inside the beaker and bend back the top to secure it in place against the edge of the glass. Attach a crocodile clip to the top of the strip.
Attach the coin to another crocodile clip using the copper wire. Dangle it into the beaker so that it is hanging directly opposite the copper strip. Ensure the two do not touch each other.
Fill the beaker with copper sulfate solution so that the coin is fully submerged.
Connect the wires to your DC power source, either directly or via an ammeter if you have one. Ensure the copper strip is connected to the positive terminal of the power source and that the quarter is connected to the negative terminal. If using an ammeter, maintain a current of around 0.25 amps. Allow the current to run and inspect the coin at regular intervals until it is fully covered with a layer of copper.