NOW is a dba. Part II and part III are classroom ready and available free until 2005 for educational use. Part II covers analyzing proportion problems. Both analyses should be part of math education. However, the more useful and effective approach is known-step analysis.
People often arrive at it on their own and it comes up in schools ad hoc.
It is the easiest approach to learn, as no algebra or fraction forming is required. Further, utilizing them follows cut and dried procedures, which are clearly formulated and explainable. Learning these and how to apply them is a far more effective approach than the conventional one of picking them up ad hoc through experiences related in other ways, as gifted persons do on their own. To many, analyzing is best left to the subject-area teachers, as it distracts from conventional math study. The texts are organized around learning these skills singly with how to apply them.