Duncan, a project manager, has to create a work breakdown structure (WBS) for a new project. He gathers the project team and provides them with a pad of sticky-notes. After defining the project objectives and the major activities that would need to be done to achieve those objectives, he asks his team members to write all the tasks that they think would be required to complete the project on the sticky-notes. These notes are then stuck on a wall in a sequential manner. In this scenario, Duncan uses a(n) ___ to create the WBS.