Which document is essential for proposing changes to a project's scope or schedule?

The change order is the essential document for proposing changes to a project's scope or schedule because it formally outlines the proposed adjustments and the rationale behind them. Change orders serve as a written record that delineates specific changes to the existing agreement, including any alterations to the project timeline, costs, or work requirements. This document is critical for managing contracts, as it ensures that all parties involved are aware of and agree to the modifications being made.

In contrast, a request for information is typically used to clarify aspects of the project rather than propose changes. A contract amendment involves a broader modification to the contract terms and conditions but is usually a more complex process than a change order. A progress report provides updates on the current status of the project but does not facilitate the formal process of altering the scope or schedule itself. Thus, the change order is the most relevant and necessary document for implementing changes during the project execution phase.