To scope means breaking down a project into more manageable parts. The tool gives a better overview of the project, and gives you a better understanding of which parts are beneath the goals you are setting and also which resources are needed.
Use the model to break down your goals into clear goals. Scoping is a useful tool in the beginning of a project, and while it is ongoing, to see if any new dilemmas has occurred. This process is best described by the rolling wave concept, pictured further down.
The Rolling wave describes the level of knowledge you are possessing at different times of the project. E.g. You are managing a project and you know that you need 10 people at the moment to do the current project goals, but will they be working on the same project goals in three months? The further you get in the project, the more you will know but it also describes the difficulty of knowing how many resources are needed. By using the break down structure you can make a more precise estimate, and this is when scoping is useful.
Scoping is a general tool and can be used in many varieties. It can limit your sensing of new opportunities if you make the break down structure and only sticks to the original scoping plan and not being agile. This is always important to assess. The goals has to be updated ongoing in order to be used. With outdated information the resources is often different than planned. When scoping it is necessary to be specific in order to have manageable goals.