Lean employs many problem-solving tools to address issues with or brainstorm improvements for work processes. A3 reports are a written tool that can help with brainstorming and solution efforts.
The name A3 report comes from an international paper size (approximately 11 x 17 inches). The size of the paper, though, isn't the most important part of a report. The reason one of these reports matters is the single sheet of paper helps keep the report concise and to-the-point. It also allows for the use of helpful visuals and a clear plan of suggested actions.
An A3 report typically contains information about the current state of a process, ideas for improvement, and sections about implementing and following up on improvements.
These reports often follow the steps of the PDCA cycle. Participants in a problem-solving process PLAN (assess current state and propose solutions), DO (implement solutions), CHECK (follow up on solutions), and ACT (standardize solutions that are effective). The A3 report can help communicate this information quickly and in an easy-to-digest fashion.