The science achievement of American students ages 9, 13, and 17 was measured during the 1976-77 school year. Overall, 543 different questions were asked in the cognitive assessment of science at the three age levels. The questions were developed according to a two-dimensional matrix. One dimension, the classification of the cognitive abilities required to answer specific science questions, was divided into four categories: (1) knowledge; (2) comprehension; (3) application; and (4) analysis, synthesis, and evaluation. The other dimension divided the domain of science into three major areas: content, process, and science and society. The questions illustrate various topics of the biological sciences, earth sciences, physical sciences, and integrated topics such as equilibrium, evolution, and probability. This document gives examples of several types of questions, and gives a summary of student performance categorized according to age, sex, ethnic background, region, size and type of community, and level of parental education. (BB) Primary type of information provided by report: Results (Selective).