What is an activity ID?
An activity ID is a unique identifier for a particular activity. In Watershed, an activity could be anything you want to measure (i.e. - taking a quiz, filling out a survey, watching a video, etc). Watershed uses activity IDs to group information related to your activity.
Activity IDs look like URLs. Some examples:
Learn more here about activities and activity IDs here: http://tincanapi.com/2013/07/10/deep-dive-activity/