This two-part course takes a practical approach to introduce attendees to the principles, methods and tools for task modelling. Part 1: A non-technical introduction demonstrates that task models can be the corner stone of successful design of interactive systems. Part 2: A more technical interactive hands-on exercise of how to "do it right", such as: How to go from task analysis to task models? How to assess (through analysis and simulation) that a task model is correct? How to identify complexity of user tasks and how to reduce it? How to identify tasks that are good candidate for migration either towards automation or other users? How to take into account user errors in task modelling? And more...