An overview of results from the National Assessment of Educational Progress in reading, science, and mathematics for American students during the 1970's -- ages 9, 13, and 17 -- is presented. Results are for three learning areas commonly accepted as critical to the maintenance of our increasingly technological society. Data on performance have been analyzed using "achievement class" and modal grade -- a new departure for National Assessment. The report attempts to answer such questions as: Were the performance patterns different in these three areas? Were the patterns different for low achievers and for high achievers? Were the performance patterns different for students in their modal grades and students below modal grades? Primary type of information provided by report: Results (Technical) (Overview). (Author/PN)