Take out a blank sheet of paper and write the subject you want to learn at the top. Write out what you know about the subject as if you were teaching it to a child. Not your smart adult friend but rather an 8-year-old who has just enough vocabulary and attention span to understand basic concepts and relationships. A lot of people tend to use complicated vocabulary and jargon to mask when they don't understand something. The problem is we only fool ourselves because we don't know that we don't understand. In addition, using jargon conceals our misunderstanding from those around us.