Independent variable: Time
Dependent variable: Temperature of water in thermos
Best thermos: Bottle A, because it kept the water hot for the longest amount of time, had a very slow temperature decline over the time period whereas other thermos water temperatures dropped alot.
Least Effective Thermos: Bottle D, lots temperature the quickest at the fastest rate, lost the most heat over the entire time of the experiment between the 4 thermos tested.