The number of minutes and clips of video recording vary by discipline. The best source of information about minutes and clips is the description for Task 2 in the handbook. Nevertheless, all areas are permitted either 15 or 20 minutes of video instruction. Elementary literacy, elementary mathematics, and secondary mathematics may submit one clip up to 15 minutes, or two clips totaling up to 15 minutes. Alternatively, English language arts, performing arts, and secondary science submit two clips, totaling up to 20 minutes. And again, health education and visual arts may submit one clip up to 20 minutes or two clips totaling up to 20 minutes. All of the disciplines shown here include two optional clips. Candidates may include a three minute clip showing student voice and a five minute clip showing academic language. Optional clips do not contribute to the totals associated with instruction clips. For example, a portfolio in visual arts may include one 20 minute clip showing instruction, another three minute clip of student voice, and another five minute clip of academic language, for a total of 28 minutes.
Despite this groundwork, Babbage's work fell into historical obscurity, and the Analytical Engine was unknown to builders of electro-mechanical and electronic computing machines in the 1930s and 1940s when they began their work, resulting in the need to re-invent many of the architectural innovations Babbage had proposed. Howard Aiken , who built the quickly-obsoleted electromechanical calculator, the Harvard Mark I , between 1937 and 1945, praised Babbage's work likely as a way of enhancing his own stature, but knew nothing of the Analytical Engine's architecture during the construction of the Mark I, and considered his visit to the constructed portion of the Analytical Engine "the greatest disappointment of my life".  The Mark I showed no influence from the Analytical Engine and lacked the Analytical Engine's most prescient architectural feature, conditional branching .  J. Presper Eckert and John W. Mauchly similarly were not aware of the details of Babbage's Analytical Engine work prior to the completion of their design for the first electronic general-purpose computer, the ENIAC .