Early in the 20th Century, a commission funded by Andrew Carnegie's philanthropy met to set standards for the measurement and reporting of secondary education in the United States. One of the recommendations of the commission was to standardize the reporting of the quantity of secondary school work by assigning one unit of value to a subject taught one hour per day, five days per week, for one academic year. Generically, this has been known as an "annual unit of high school work". The Carnegie Unit is the most common quantitative reporting measure in the United States. A subject taught one hour per day (50 to 60 minutes), five days per week, for one 16-week semester will have 65 to 80 hours of teaching time. This is equivalent to one-half credit. If the class is taken for two semesters (130 to 160 hours), this is equivalent to one full credit or one Carnegie Unit.