Creating Scenarios & Tasks for User Testing
A scenario is a story about, and general description of the context around, the tasks that will be performed in the user testing session. Though they aren't always necessary, if there is any back-story they need to understand the context it can help participants to better put themselves in the shoes of the user they are representing.
Conversely, the task is more specific and describes the action the user will perform within the system. It is important do describe the task in layman's terms, without using the name of any features or links you'd like a user to find--a good task description will make the task explicit without leading the user to any particular path of completing the task. It is also important to make sure that you don't use jargon in your user testing task descriptions, as it may confuse and/or intimidate test participants.
Keep in mind that it may be necessary to define unique tasks for different Personas or roles. In some situations, such as when designing UI components, it may also be helpful to write scenarios which describe more than one context. In this situation, it can make the test more cohesive if you have the participant work through several tasks that all naturally flow together in a single scenario like they would in the real world.
For instance, if you were trying to test a 'Pager' widget, you could test how it works in many different places in the Sakai learning management system. An initial scenario could have the participant pretend he is a student who is working on the latest assignment for his Biology 101 class. He finds a course announcement from last week with a link to the assignment, and then finds a particular message (in the Forum/Discussion tool) to help him do the assignment. Before he submits the assignment, he reviews his grade for his past assignments (in the Gradebook) to try to figure out how good of a grade he needs on this assignment to be on track for an A in the course. To finish the assignment, he then needs to review some materials from another site from last semester which he's hidden, so he (goes to Worksite Setup and) finds the site in a somewhat but not too large list (perhaps 30 items, enough to initiate paging) of his sites.
If it's possible for the participant to play multiple roles, he may then act as an instructor for another scenario. First he finds the student's assignment (in the Drop Box). He reads it and looks up the students' grades (in the Gradebook) to see how he's doing overall, then enters the grade for this assignment. As the student had a problem with a question that many other students had, he goes to the quiz (which he created in the Quiz & Survey tool) to find out how the question looked to students. Finally, the instructor finds a site for an Accessibility group on campus he's just found out about and is interested in and joins it (in Worksite Setup).
User Testing Scenario and Task Examples: