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- Left column (Add activity): user can add an activity, and change properties related to that activity such as its location, name, earliest start time and latest end time (e.g., museum closing times). When an activity is added, it appears in the list of activities (center) column.
- Center column (List of Activities): A list of all activities that the user wants to do, but have not yet been scheduled. This is conceptually a TODO list: activities in this column have a duration (which can be changed by the user), but haven't been given a specific start time. Activities move between this and the right column as the schedule changes.
- Right column (Schedule): The concrete schedule of activities. This column has an hour-by-hour calendar feel; activities placed on it have a duration and start time and abide by the following constraints. First, no activity may overlap with another activity (you can't be in two places at the same time). Second, no activity can start before its earliest start time (specified in the left column) or after its latest end time (you can't visit a museum after it has closed). Each activity has a "locked?" button which indicates whether the start time is flexible (this will be explained below).
The final design has the following flow. The user adds a set of activities in the left column. Then, the user constructs a final schedule through an iterative process of moving activities between the list of activities and schedule column. When the user moves an activity from the list of activities to the schedule, some activity from the schedule may be displaced and moved back to the list of activities. The application provides a "schedule these activities for me" button, which tries to schedule all of the remaining activities in the list of activities in one click. When the user is satisfied with the state of the schedule column, the scenario is complete.
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