An example of an internal schedule is a workplace schedule, which lists the hours that specific employees are expected to be in a workplace, ensure sufficient staffing at all times while in some instances avoiding overstaffing. A work schedule for a business that is open to the public must correspond to the hours of operation of the business, so that employees are available at times when customers are able to use the services of the business. One common method of scheduling employees to ensure the availability of appropriate resources is a Gantt chart. Another example of an internal schedule is the class schedule of an individual student, indicating what days and times their classes will be held.