Relationships are really one of the most important part of a schedule. Activities and work breakdown structure without relationships are really just an organized list. Relationships define what activities are before and after an activity and are typically represented on a schedule with black arrows. There are different types of activities but the most common and widely used is finish to start. A good example of how an activity should affect your schedule, a finish to start activity would be applied to the drywall as it relates to the painting activity, meaning the painting work would only start after the drywall work was done.