Thinking is central to who we are. What is thinking? Have you ever been asked this question? Have you ever asked yourself this question. Have you ever gone to a dictionary to find a definition? If we don't know what thinking is we cannot intentionally improve it or measure improvement. Plainly put, we can't knowingly improve or measure what we don't know. Have we, have you ever gone to a dictionary to find this vital definition? We haven't given thinking a second thought. We have taken thinking for granted though it grants us everything. The Learning Curve provides a definition that can be understood by and adolescent and measured. Further this definitions are backed up by your life experience. Additionally, as astrophysicist Carl Sagan observed: "Extraordinary claims require extraordinary evidence." There is 30 pages of every-day observations that support the definition.