The author tries to make a more exact evaluation of the standard of knowledge in social sciences of the Nine-Year Basic School pupils. For this purpose he reduces the extensive information provided by the school to the question of the immediate social science vocabulary, i. e. terms whose meaning is connected with one of the social sciences. Then he traces the occurrence of these terms in the textbooks, both their total number and their rate of occurrence in relation to the other neutral terms in the text and their recurrence. He compares the general distribution of frequencies of social science terms in the textbooks with the distribution of the occurrence of the same terms in ordinary standard Czech and in scientific Czech. According to the indices under observation the structure of social science textbooks appears to be to a great extent subjective. However, as similar statements can concern only textbooks and not the actual social science process of learning, the author tries to find out what it is that turns a mere sum of meanings in a certain subject into real knowledge and finds it is abstraction as the most important learning activity. On the basis of this conclusion he then prepares comprehension tests of the meaning of social science terms from the textbooks. He eliminates from complete sets of excerpted social science terms representative samples of words, divides these words into several groups according to the degree of abstraction of their meanings and gives these tests to a sample of 770 pupils of Prague Basic Nine-Year Schools to find out the dependence of correct comprehension of the meanings of social science terms (as given in the textbook contexts) on the degree of abstraction of these terms, on their frequency in the textbook used in the previous year and on their frequency during all the years of school attendance, and also the dependence of the individual pupils’ performances in the test on the grades in the subject concerned attained by them for their classroom work. The resultant correlations do not prove a univocal relation of the standard of knowledge to the frequency of the terms met with either in the textbooks of the previous year or the aggregate frequency of several previous years; but they do show differences between test results, i. e. between the level of comprehension of the meanings of social science terms used by the pupils and the grading of the pupils in the subject concerned, and finally, the most important of all, they do prove significant dependence on the degree of abstraction of social science terms for the comprehension of their meanings. There was a general tendency to distort the meanings of the more abstract terms, nearly always by unsuitably concretizing the terms or sometimes by personification. The author sees the causes of this not only in the textbooks and the style of imparting knowledge as it is organized by the school, but also in the complex of broader phenomena of social signification.