97U20 Analysis of textbooks, development and evaluation of textbooks. Textbook use in the classroom
97U30 Teacher manuals and planning aids
97U40 Problem books; student competitions, examination questions
97U50 Computer assisted instruction and programmed instruction
97U60 Manipulative materials and their use in the classroom {For research aspects see 97C80}
97U70 Technological tools (computers, calculators, software, etc.) and their use in the classroom
97U80 Audiovisual media and their use in instruction
97U99 None of the above, but in this section