Summary of Understanding A3 Thinking

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Understanding A3 Thinking book summary

Editorial Rating



  • Applicable
  • Well Structured
  • Concrete Examples


This concise manual for developing A3 reports goes well beyond the format and function of the report itself. The authors explore the history behind Toyota’s use of the A3 approach, including its version of the scientific method, “Plan-Do-Check-Act” (“PDCA”). The authors make the point repeatedly that “A3 thinking” and the underlying philosophy of continuous improvement matter far more than the layout of reports. At Toyota, use of the A3 and PDCA methods has forged generations of critical thinkers and problem solvers, granting the firm more than six decades of near unparalleled success. 

About the Authors

Durward K. Sobek II teaches industrial and management engineering at Montana State University. Art Smalley consults with firms worldwide through his firm, Art of Lean.


For more than 60 years, Toyota has remained among the world’s most successful, admired and emulated companies.

Since Durward Sobek and Art Smalley wrote Understanding A3 Thinking in 2008, the methods they describe have only grown more popular. These ideas and methods contributed to the burgeoning Lean movement.

Toyota teaches A3 thinking to managers because it demands rigorous problem solving and logical thinking.

The A3 method has its roots in the Plan-Do-Check-Act (PDCA) cycle – a continuous improvement process that Toyota learned from American engineer W. Edwards Deming, who worked with Japanese firms after World War II. Deming influenced Toyota’s founder Sakichi Toyoda and his son, Kiichiro.

In the PDCA process, managers do the following:

  • Plan – Develop a hypothesis.
  • Do – Swiftly implement the plan in order to test the hypothesis and experiment.
  • Check – Measure the results.
  • Act – Analyze the results and apply them, or adjust and start ...

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