Plaisant, CatherineShneiderman, BenThis article describes four different user interfaces supporting scheduling two state (ON/OFF) devices over time periods ranging from minutes to days. The touchscreen-based user interfaces including a digital, 12-hour clock, 24-hour linear and 24-hour dial prototypes are described and compared on a feature by feature basis. An informal usability test with 14 subjects, feedback from more than 30 reviewers, and the flexibility to add functions favors the 24-hour linear version. (Also cross-referenced as CAR-TR-472)en-USTechnical Report