Self-evaluation leading to sustained self-improvement is therefore at the core of the school improvement policy. Effective self-evaluation, and the actions that flow from it, should deliver improved educational outcomes and experiences for all pupils. Self-evaluation must be an integral part of the school development planning process with the resulting actions and targets captured in School Development Plans (SDPs).
The SDP is a strategic plan for improvement. It should bring together, in a clear and simple way, the school’s priorities, the main measures it will take to raise standards, the resources dedicated to these, and the key outcomes and targets it intends to achieve.
These paragraphs are taken from the Department for Education website. For more information see here.