The certificated flight instructor (CFI) and private pilot receiving instruction were conducting an instrument approach to a 2,500-foot long runway in instrument meteorological conditions (IMC). The pilot receiving instruction was at the controls. As the airplane reached the minimum descent altitude, the pilot initiated a circle-to-land on the opposite runway. The CFI then said, "no," took control of the airplane, and conducted a "steep" turn to land on the approach runway. The pilot stated that they "had too much airspeed and floated almost halfway down the runway." Upon touchdown, the pilot reported "hydroplaning" on the wet runway. The airplane departed the end of the runway, slid down a grassy hill, and came to rest in a ditch, resulting in substantial damage to the firewall. The CFI stated "there was some confusion" regarding who was at the controls during touchdown, and he "should have taken over sooner" than he did. The pilot and the CFI reported no mechanical malfunctions or failures. The nearest weather reporting station, located approximately 15 nautical miles north of the accident site, reported winds from 310 degrees at 3 knots and 10 miles visibility around the time of the accident. The report also indicated that rain had ended about 15 minutes prior to the accident.