Basically you need to get several goldfish and different containers that are a different water temperature.
Explanation:
Get your goldfish. About 3-4 because the water should affect each of them about the same, so you want to make sure that it is the same outcome each time and not just a fluke.
Get your water containers. Ideal water for goldfish is about 68-74 degrees. Anything below 68 is considered to cold, and anything about 74 degrees would be considered to hot. However, with this experiment, you will need "cold" water (anything under 67 degrees ideally anything under 55 degrees would be nice and "cold" for the fish), ideal water (68-74 degrees), and then "hot" water (anything above 75 degrees. Ideally about 77 - 85 degrees would be hot enough for them)
Next I'd say form your hypothesis. When water is too cold, goldfish may stop eating, begin hibernating or die. When the water is to hot goldfish will become very stressed, and can overheat and die. So, choose a hypothesis from that.
Your independent variable would be the water temperature, because it doesn't depend on anything. While how your goldfish act would be the dependent variable because they act according to the water temperature.
Good luck with your experiment, and this is all I got for ya! Good luck!
