Anthony P. Solli
The historical part of this unit may be used in any grade level, preferably middle school. The activities part could be used in any middle school level, although it is recommended for average and above average groups working in small groups or independently. It also may be used as a motivational or summary part of a geometry unit or pre algebra course.
The length of time needed could be a week or two, depending on the amount of time you would spend on the history of ~r and doing all or some of the suggested activities.